pdf_view_web_plugin.h

// Copyright 2020 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#ifndef PDF_PDF_VIEW_WEB_PLUGIN_H_
#define PDF_PDF_VIEW_WEB_PLUGIN_H_

#include <stdint.h>

#include <memory>
#include <string>
#include <vector>

#include "base/callback_forward.h"
#include "base/containers/flat_set.h"
#include "base/containers/queue.h"
#include "base/i18n/rtl.h"
#include "base/memory/raw_ptr.h"
#include "base/memory/weak_ptr.h"
#include "base/strings/string_piece_forward.h"
#include "base/values.h"
#include "cc/paint/paint_image.h"
#include "mojo/public/cpp/bindings/associated_remote.h"
#include "mojo/public/cpp/bindings/receiver.h"
#include "pdf/loader/url_loader.h"
#include "pdf/mojom/pdf.mojom.h"
#include "pdf/pdf_accessibility_action_handler.h"
#include "pdf/pdf_engine.h"
#include "pdf/pdf_view_plugin_base.h"
#include "pdf/pdfium/pdfium_form_filler.h"
#include "pdf/post_message_receiver.h"
#include "pdf/preview_mode_client.h"
#include "pdf/v8_value_converter.h"
#include "third_party/blink/public/platform/web_string.h"
#include "third_party/blink/public/platform/web_text_input_type.h"
#include "third_party/blink/public/web/web_plugin.h"
#include "third_party/blink/public/web/web_plugin_container.h"
#include "third_party/blink/public/web/web_plugin_params.h"
#include "third_party/blink/public/web/web_print_params.h"
#include "third_party/skia/include/core/SkColor.h"
#include "ui/base/cursor/mojom/cursor_type.mojom-shared.h"
#include "ui/gfx/geometry/rect.h"
#include "ui/gfx/geometry/size.h"
#include "ui/gfx/geometry/vector2d_f.h"
#include "v8/include/v8.h"

namespace blink {
class WebAssociatedURLLoader;
class WebURL;
class WebURLRequest;
struct WebAssociatedURLLoaderOptions;
struct WebPrintPresetOptions;
}  // namespace blink

namespace gfx {
class PointF;
class Range;
}  // namespace gfx

namespace net {
class SiteForCookies;
}  // namespace net

namespace printing {
class MetafileSkia;
}  // namespace printing

namespace chrome_pdf {

class MetricsHandler;
class PDFiumEngine;
class PdfAccessibilityDataHandler;
class Thumbnail;

class PdfViewWebPlugin final : public PdfViewPluginBase,
                               public blink::WebPlugin,
                               public pdf::mojom::PdfListener,
                               public UrlLoader::Client,
                               public PostMessageReceiver::Client,
                               public PdfAccessibilityActionHandler,
                               public PreviewModeClient::Client {
 public:
  // Must match `SaveRequestType` in chrome/browser/resources/pdf/constants.ts.
  enum class SaveRequestType {
    kAnnotation = 0,
    kOriginal = 1,
    kEdited = 2,
  };

  // Provides services from the plugin's container.
  class Client : public V8ValueConverter {
   public:
    virtual ~Client() = default;

    virtual base::WeakPtr<Client> GetWeakPtr() = 0;

    // Creates a new `PDFiumEngine`.
    virtual std::unique_ptr<PDFiumEngine> CreateEngine(
        PDFEngine::Client* client,
        PDFiumFormFiller::ScriptOption script_option);

    // Passes the plugin container to the client. This is first called in
    // `Initialize()`, and cleared to null in `Destroy()`. The container may
    // also be null for testing.
    virtual void SetPluginContainer(blink::WebPluginContainer* container) = 0;

    // Returns the plugin container set by `SetPluginContainer()`.
    virtual blink::WebPluginContainer* PluginContainer() = 0;

    // Returrns the document's site for cookies.
    virtual net::SiteForCookies SiteForCookies() const = 0;

    // Resolves `partial_url` relative to the document's base URL.
    virtual blink::WebURL CompleteURL(
        const blink::WebString& partial_url) const = 0;

    // Enqueues a "message" event carrying `message` to the plugin embedder.
    virtual void PostMessage(base::Value::Dict message) {}

    // Invalidates the entire web plugin container and schedules a paint of the
    // page in it.
    virtual void Invalidate() = 0;

    // Notifies the container about which touch events the plugin accepts.
    virtual void RequestTouchEventType(
        blink::WebPluginContainer::TouchEventRequestType request_type) = 0;

    // Notify the web plugin container about the total matches of a find
    // request.
    virtual void ReportFindInPageMatchCount(int identifier,
                                            int total,
                                            bool final_update) = 0;

    // Notify the web plugin container about the selected find result in plugin.
    virtual void ReportFindInPageSelection(int identifier, int index) = 0;

    // Notify the web plugin container about find result tickmarks.
    virtual void ReportFindInPageTickmarks(
        const std::vector<gfx::Rect>& tickmarks) = 0;

    // Returns the device scale factor.
    virtual float DeviceScaleFactor() = 0;

    // Gets the scroll position.
    virtual gfx::PointF GetScrollPosition() = 0;

    // Tells the embedder to allow the plugin to handle find requests.
    virtual void UsePluginAsFindHandler() = 0;

    // Calls underlying WebLocalFrame::SetReferrerForRequest().
    virtual void SetReferrerForRequest(blink::WebURLRequest& request,
                                       const blink::WebURL& referrer_url) = 0;

    // Calls underlying WebLocalFrame::Alert().
    virtual void Alert(const blink::WebString& message) = 0;

    // Calls underlying WebLocalFrame::Confirm().
    virtual bool Confirm(const blink::WebString& message) = 0;

    // Calls underlying WebLocalFrame::Prompt().
    virtual blink::WebString Prompt(const blink::WebString& message,
                                    const blink::WebString& default_value) = 0;

    // Calls underlying WebLocalFrame::TextSelectionChanged().
    virtual void TextSelectionChanged(const blink::WebString& selection_text,
                                      uint32_t offset,
                                      const gfx::Range& range) = 0;

    // Calls underlying WebLocalFrame::CreateAssociatedURLLoader().
    virtual std::unique_ptr<blink::WebAssociatedURLLoader>
    CreateAssociatedURLLoader(
        const blink::WebAssociatedURLLoaderOptions& options) = 0;

    // Notifies the frame widget about the text input type change.
    virtual void UpdateTextInputState() = 0;

    // Notifies the frame widget about the selection bound change.
    virtual void UpdateSelectionBounds() = 0;

    // Gets the embedder's origin as a serialized string.
    virtual std::string GetEmbedderOriginString() = 0;

    // Returns whether the plugin container's frame exists.
    virtual bool HasFrame() const = 0;

    // Notifies the frame's client that the plugin started loading.
    virtual void DidStartLoading() = 0;

    // Notifies the frame's client that the plugin stopped loading.
    virtual void DidStopLoading() = 0;

    // Prints the plugin element.
    virtual void Print() {}

    // Sends over a string to be recorded by user metrics as a computed action.
    // When you use this, you need to also update the rules for extracting known
    // actions in tools/metrics/actions/extract_actions.py.
    virtual void RecordComputedAction(const std::string& action) {}

    // Creates an implementation of `PdfAccessibilityDataHandler` catered to the
    // client.
    virtual std::unique_ptr<PdfAccessibilityDataHandler>
    CreateAccessibilityDataHandler(
        PdfAccessibilityActionHandler* action_handler);
  };

  PdfViewWebPlugin(std::unique_ptr<Client> client,
                   mojo::AssociatedRemote<pdf::mojom::PdfService> pdf_service,
                   const blink::WebPluginParams& params);
  PdfViewWebPlugin(const PdfViewWebPlugin& other) = delete;
  PdfViewWebPlugin& operator=(const PdfViewWebPlugin& other) = delete;

  // blink::WebPlugin:
  bool Initialize(blink::WebPluginContainer* container) override;
  void Destroy() override;
  blink::WebPluginContainer* Container() const override;
  v8::Local<v8::Object> V8ScriptableObject(v8::Isolate* isolate) override;
  bool SupportsKeyboardFocus() const override;
  void UpdateAllLifecyclePhases(blink::DocumentUpdateReason reason) override;
  void Paint(cc::PaintCanvas* canvas, const gfx::Rect& rect) override;
  void UpdateGeometry(const gfx::Rect& window_rect,
                      const gfx::Rect& clip_rect,
                      const gfx::Rect& unobscured_rect,
                      bool is_visible) override;
  void UpdateFocus(bool focused, blink::mojom::FocusType focus_type) override;
  void UpdateVisibility(bool visibility) override;
  blink::WebInputEventResult HandleInputEvent(
      const blink::WebCoalescedInputEvent& event,
      ui::Cursor* cursor) override;
  void DidReceiveResponse(const blink::WebURLResponse& response) override;
  void DidReceiveData(const char* data, size_t data_length) override;
  void DidFinishLoading() override;
  void DidFailLoading(const blink::WebURLError& error) override;
  bool SupportsPaginatedPrint() override;
  bool GetPrintPresetOptionsFromDocument(
      blink::WebPrintPresetOptions* print_preset_options) override;
  int PrintBegin(const blink::WebPrintParams& print_params) override;
  void PrintPage(int page_number, cc::PaintCanvas* canvas) override;
  void PrintEnd() override;
  bool HasSelection() const override;
  blink::WebString SelectionAsText() const override;
  blink::WebString SelectionAsMarkup() const override;
  bool CanEditText() const override;
  bool HasEditableText() const override;
  bool CanUndo() const override;
  bool CanRedo() const override;
  bool CanCopy() const override;
  bool ExecuteEditCommand(const blink::WebString& name,
                          const blink::WebString& value) override;
  blink::WebURL LinkAtPosition(const gfx::Point& /*position*/) const override;
  bool StartFind(const blink::WebString& search_text,
                 bool case_sensitive,
                 int identifier) override;
  void SelectFindResult(bool forward, int identifier) override;
  void StopFind() override;
  bool CanRotateView() override;
  void RotateView(blink::WebPlugin::RotationType type) override;

  bool ShouldDispatchImeEventsToPlugin() override;
  blink::WebTextInputType GetPluginTextInputType() override;
  gfx::Rect GetPluginCaretBounds() override;
  void ImeSetCompositionForPlugin(
      const blink::WebString& text,
      const std::vector<ui::ImeTextSpan>& ime_text_spans,
      const gfx::Range& replacement_range,
      int selection_start,
      int selection_end) override;
  void ImeCommitTextForPlugin(
      const blink::WebString& text,
      const std::vector<ui::ImeTextSpan>& ime_text_spans,
      const gfx::Range& replacement_range,
      int relative_cursor_pos) override;
  void ImeFinishComposingTextForPlugin(bool keep_selection) override;

  // PDFEngine::Client:
  void ProposeDocumentLayout(const DocumentLayout& layout) override;
  void UpdateCursor(ui::mojom::CursorType new_cursor_type) override;
  void UpdateTickMarks(const std::vector<gfx::Rect>& tickmarks) override;
  void NotifyNumberOfFindResultsChanged(int total, bool final_result) override;
  void NotifySelectedFindResultChanged(int current_find_index) override;
  void GetDocumentPassword(
      base::OnceCallback<void(const std::string&)> callback) override;
  void Beep() override;
  void Alert(const std::string& message) override;
  bool Confirm(const std::string& message) override;
  std::string Prompt(const std::string& question,
                     const std::string& default_answer) override;
  std::string GetURL() override;
  void Print() override;
  void SubmitForm(const std::string& url,
                  const void* data,
                  int length) override;
  std::unique_ptr<UrlLoader> CreateUrlLoader() override;
  std::vector<SearchStringResult> SearchString(const char16_t* string,
                                               const char16_t* term,
                                               bool case_sensitive) override;
  void DocumentHasUnsupportedFeature(const std::string& feature) override;
  bool IsPrintPreview() const override;
  SkColor GetBackgroundColor() const override;
  void CaretChanged(const gfx::Rect& caret_rect) override;
  void EnteredEditMode() override;
  void SetSelectedText(const std::string& selected_text) override;
  void SetLinkUnderCursor(const std::string& link_under_cursor) override;
  bool IsValidLink(const std::string& url) override;

  // pdf::mojom::PdfListener:
  void SetCaretPosition(const gfx::PointF& position) override;
  void MoveRangeSelectionExtent(const gfx::PointF& extent) override;
  void SetSelectionBounds(const gfx::PointF& base,
                          const gfx::PointF& extent) override;

  // UrlLoader::Client:
  bool IsValid() const override;
  blink::WebURL CompleteURL(const blink::WebString& partial_url) const override;
  net::SiteForCookies SiteForCookies() const override;
  void SetReferrerForRequest(blink::WebURLRequest& request,
                             const blink::WebURL& referrer_url) override;
  std::unique_ptr<blink::WebAssociatedURLLoader> CreateAssociatedURLLoader(
      const blink::WebAssociatedURLLoaderOptions& options) override;

  // PostMessageReceiver::Client:
  void OnMessage(const base::Value::Dict& message) override;

  // PaintManager::Client:
  void InvalidatePluginContainer() override;
  void UpdateSnapshot(sk_sp<SkImage> snapshot) override;
  void UpdateScale(float scale) override;
  void UpdateLayerTransform(float scale,
                            const gfx::Vector2dF& translate) override;

  // PdfAccessibilityActionHandler:
  void EnableAccessibility() override;
  void HandleAccessibilityAction(
      const AccessibilityActionData& action_data) override;

  // PreviewModeClient::Client:
  void PreviewDocumentLoadComplete() override;
  void PreviewDocumentLoadFailed() override;

  // Initializes the plugin for testing, bypassing certain consistency checks.
  bool InitializeForTesting();

  const gfx::Rect& GetPluginRectForTesting() const { return plugin_rect(); }

  float GetDeviceScaleForTesting() const { return device_scale(); }

 protected:
  // PdfViewPluginBase:
  std::unique_ptr<PDFiumEngine> CreateEngine(
      PDFEngine::Client* client,
      PDFiumFormFiller::ScriptOption script_option) override;
  const PDFiumEngine* engine() const override;
  PDFiumEngine* engine() override;
  base::WeakPtr<PdfViewPluginBase> GetWeakPtr() override;
  void OnPrintPreviewLoaded() override;
  void OnDocumentLoadComplete() override;
  void SendMessage(base::Value::Dict message) override;
  void SetFormTextFieldInFocus(bool in_focus) override;
  void SetAccessibilityDocInfo(AccessibilityDocInfo doc_info) override;
  void SetAccessibilityPageInfo(AccessibilityPageInfo page_info,
                                std::vector<AccessibilityTextRunInfo> text_runs,
                                std::vector<AccessibilityCharInfo> chars,
                                AccessibilityPageObjects page_objects) override;
  void SetAccessibilityViewportInfo(
      AccessibilityViewportInfo viewport_info) override;
  void SetContentRestrictions(int content_restrictions) override;
  void DidStartLoading() override;
  void DidStopLoading() override;
  void NotifySelectionChanged(const gfx::PointF& left,
                              int left_height,
                              const gfx::PointF& right,
                              int right_height) override;
  void UserMetricsRecordAction(const std::string& action) override;
  bool full_frame() const override;
  const gfx::Size& plugin_dip_size() const override;
  const gfx::Rect& plugin_rect() const override;
  float device_scale() const override;
  bool needs_reraster() const override;
  base::i18n::TextDirection ui_direction() const override;
  bool received_viewport_message() const override;
  void PrepareForFirstPaint(std::vector<PaintReadyRect>& ready) override;

 private:
  // Callback that runs after `LoadUrl()`. The `loader` is the loader used to
  // load the URL, and `result` is the result code for the load.
  using LoadUrlCallback =
      base::OnceCallback<void(std::unique_ptr<UrlLoader> loader,
                              int32_t result)>;

  // Metadata about an available preview page.
  struct PreviewPageInfo {
    // Data source URL.
    std::string url;

    // Page index in destination document.
    int dest_page_index = -1;
  };

  // Call `Destroy()` instead.
  ~PdfViewWebPlugin() override;

  bool InitializeCommon();

  // Sends whether to do smooth scrolling.
  void SendSetSmoothScrolling();

  // Handles `LoadUrl()` result for the main document.
  void DidOpen(std::unique_ptr<UrlLoader> loader, int32_t result);

  // Updates the scroll position, which is in CSS pixels relative to the
  // top-left corner.
  void UpdateScroll(const gfx::PointF& scroll_position);

  // Loads `url`, invoking `callback` on receiving the initial response.
  void LoadUrl(base::StringPiece url, LoadUrlCallback callback);

  // Handles `Open()` result for `form_loader_`.
  void DidFormOpen(int32_t result);

  // Message handlers.
  void HandleDisplayAnnotationsMessage(const base::Value::Dict& message);
  void HandleGetNamedDestinationMessage(const base::Value::Dict& message);
  void HandleGetPasswordCompleteMessage(const base::Value::Dict& message);
  void HandleGetSelectedTextMessage(const base::Value::Dict& message);
  void HandleGetThumbnailMessage(const base::Value::Dict& message);
  void HandlePrintMessage(const base::Value::Dict& /*message*/);
  void HandleRotateClockwiseMessage(const base::Value::Dict& /*message*/);
  void HandleRotateCounterclockwiseMessage(
      const base::Value::Dict& /*message*/);
  void HandleSaveAttachmentMessage(const base::Value::Dict& message);
  void HandleSaveMessage(const base::Value::Dict& message);
  void HandleSelectAllMessage(const base::Value::Dict& /*message*/);
  void HandleSetBackgroundColorMessage(const base::Value::Dict& message);
  void HandleSetPresentationModeMessage(const base::Value::Dict& message);
  void HandleSetTwoUpViewMessage(const base::Value::Dict& message);
  void HandleStopScrollingMessage(const base::Value::Dict& message);
  void HandleViewportMessage(const base::Value::Dict& message);

  void SaveToBuffer(const std::string& token);
  void SaveToFile(const std::string& token);

  // Recalculates values that depend on scale factors.
  void UpdateScaledValues();

  void OnViewportChanged(const gfx::Rect& new_plugin_rect_in_css_pixel,
                         float new_device_scale);

  // Text editing methods.
  bool SelectAll();
  bool Cut();
  bool Paste(const blink::WebString& value);
  bool Undo();
  bool Redo();

  // Helper method for converting IME text to input events.
  // TODO(crbug.com/1253665): Consider handling composition events.
  void HandleImeCommit(const blink::WebString& text);

  // Callback to print without re-entrancy issues. The callback prevents the
  // invocation of printing in the middle of an event handler, which is risky;
  // see crbug.com/66334.
  // TODO(crbug.com/1217012): Re-evaluate the need for a callback when parts of
  // the plugin are moved off the main thread.
  void OnInvokePrintDialog();

  void ResetRecentlySentFindUpdate();

  // Records metrics about the document metadata.
  void RecordDocumentMetrics();

  // Sends the attachments data.
  void SendAttachments();

  // Sends the bookmarks data.
  void SendBookmarks();

  // Send document metadata data.
  void SendMetadata();

  // Handles message for resetting Print Preview.
  void HandleResetPrintPreviewModeMessage(const base::Value::Dict& message);

  // Handles message for loading a preview page.
  void HandleLoadPreviewPageMessage(const base::Value::Dict& message);

  // Starts loading the next available preview page into a blank page.
  void LoadAvailablePreviewPage();

  // Handles `LoadUrl()` result for a preview page.
  void DidOpenPreview(std::unique_ptr<UrlLoader> loader, int32_t result);

  // Continues loading the next preview page.
  void LoadNextPreviewPage();

  // Sends a notification that the print preview has loaded.
  void SendPrintPreviewLoadedNotification();

  // Sends the thumbnail image data.
  void SendThumbnail(base::Value::Dict reply, Thumbnail thumbnail);

  blink::WebString selected_text_;

  std::unique_ptr<Client> const client_;

  // Used to access the services provided by the browser.
  mojo::AssociatedRemote<pdf::mojom::PdfService> const pdf_service_;

  mojo::Receiver<pdf::mojom::PdfListener> listener_receiver_{this};

  std::unique_ptr<PDFiumEngine> engine_;

  // The URL of the PDF document.
  std::string url_;

  // The callback for receiving the password from the page.
  base::OnceCallback<void(const std::string&)> password_callback_;

  // The current cursor type.
  ui::mojom::CursorType cursor_type_ = ui::mojom::CursorType::kPointer;

  blink::WebTextInputType text_input_type_ =
      blink::WebTextInputType::kWebTextInputTypeNone;

  gfx::Rect caret_rect_;

  blink::WebString composition_text_;

  // Whether the plugin element currently has focus.
  bool has_focus_ = false;

  blink::WebPluginParams initial_params_;

  v8::Persistent<v8::Object> scriptable_receiver_;

  // The current image snapshot.
  cc::PaintImage snapshot_;

  // Translate from snapshot to device pixels.
  gfx::Vector2dF snapshot_translate_;

  // Scale from snapshot to device pixels.
  float snapshot_scale_ = 1.0f;

  // The viewport coordinates to DIP (device-independent pixel) ratio.
  float viewport_to_dip_scale_ = 1.0f;

  // The device pixel to CSS pixel ratio.
  float device_to_css_scale_ = 1.0f;

  // Combined translate from snapshot to device to CSS pixels.
  gfx::Vector2dF total_translate_;

  // The plugin rect in CSS pixels.
  gfx::Rect css_plugin_rect_;

  // True if the plugin occupies the entire frame (not embedded).
  bool full_frame_ = false;

  // The background color of the PDF viewer.
  SkColor background_color_ = SK_ColorTRANSPARENT;

  // Size, in DIPs, of plugin rectangle.
  gfx::Size plugin_dip_size_;

  // The plugin rectangle in device pixels.
  gfx::Rect plugin_rect_;

  // Current device scale factor. Multiply by `device_scale_` to convert from
  // viewport to screen coordinates. Divide by `device_scale_` to convert from
  // screen to viewport coordinates.
  float device_scale_ = 1.0f;

  // True if we haven't painted the plugin viewport yet.
  bool first_paint_ = true;

  // True if last bitmap was smaller than the screen.
  bool last_bitmap_smaller_ = false;

  // True if we request a new bitmap rendering.
  bool needs_reraster_ = true;

  // The UI direction.
  base::i18n::TextDirection ui_direction_ = base::i18n::UNKNOWN_DIRECTION;

  // The scroll offset for the last raster in CSS pixels, before any
  // transformations are applied.
  gfx::Vector2dF scroll_offset_at_last_raster_;

  // If this is true, then don't scroll the plugin in response to calls to
  // `UpdateScroll()`. This will be true when the extension page is in the
  // process of zooming the plugin so that flickering doesn't occur while
  // zooming.
  bool stop_scrolling_ = false;

  // Whether the plugin has received a viewport changed message. Nothing should
  // be painted until this is received.
  bool received_viewport_message_ = false;

  // If true, the render frame has been notified that we're starting a network
  // request so that it can start the throbber. It will be notified again once
  // the document finishes loading.
  bool did_call_start_loading_ = false;

  // Used for submitting forms.
  std::unique_ptr<UrlLoader> form_loader_;

  // Handler for accessibility data updates.
  std::unique_ptr<PdfAccessibilityDataHandler> const
      pdf_accessibility_data_handler_;

  // The URL currently under the cursor.
  std::string link_under_cursor_;

  // The id of the current find operation, or -1 if no current operation is
  // present.
  int find_identifier_ = -1;

  // Whether an update to the number of find results found was sent less than
  // `kFindResultCooldown` TimeDelta ago.
  bool recently_sent_find_update_ = false;

  // Stores the tickmarks to be shown for the current find results.
  std::vector<gfx::Rect> tickmarks_;

  // Whether the document is in edit mode.
  bool edit_mode_ = false;

  // Only instantiated when not print previewing.
  std::unique_ptr<MetricsHandler> metrics_handler_;

  // Keeps track of which unsupported features have been reported to avoid
  // spamming the metrics if a feature shows up many times per document.
  base::flat_set<std::string> unsupported_features_reported_;

  // Indicates whether the browser has been notified about an unsupported
  // feature once, which helps prevent the infobar from going up more than once.
  bool notified_browser_about_unsupported_feature_ = false;

  // The metafile in which to save the printed output. Assigned a value only
  // between `PrintBegin()` and `PrintEnd()` calls.
  raw_ptr<printing::MetafileSkia> printing_metafile_ = nullptr;

  // The indices of pages to print.
  std::vector<int> pages_to_print_;

  // Assigned a value only between `PrintBegin()` and `PrintEnd()` calls.
  absl::optional<blink::WebPrintParams> print_params_;

  // For identifying actual print operations to avoid double logging of UMA.
  bool print_pages_called_;

  // Whether the plugin is loaded in Print Preview.
  bool is_print_preview_ = false;

  // Number of pages in Print Preview (non-PDF). 0 if previewing a PDF, and -1
  // if not in Print Preview.
  int print_preview_page_count_ = -1;

  // Number of pages loaded in Print Preview (non-PDF). Always less than or
  // equal to `print_preview_page_count_`.
  int print_preview_loaded_page_count_ = -1;

  // The PreviewModeClient used for print preview. Will be passed to
  // `preview_engine_`.
  std::unique_ptr<PreviewModeClient> preview_client_;

  // Engine used to render individual preview pages. This will use the
  // `PreviewModeClient` interface.
  std::unique_ptr<PDFiumEngine> preview_engine_;

  // Document load state for the Print Preview engine.
  DocumentLoadState preview_document_load_state_ = DocumentLoadState::kComplete;

  // Queue of available preview pages to load next.
  base::queue<PreviewPageInfo> preview_pages_info_;

  base::WeakPtrFactory<PdfViewWebPlugin> weak_factory_{this};
};

}  // namespace chrome_pdf

#endif  // PDF_PDF_VIEW_WEB_PLUGIN_H_