[unseasoned-pdf] Introduce PdfViewPluginBase::SendMessage()

Also implement the pure virtual method for both derived classes of
PdfViewPluginBase.

The interface will allow for PostMessage()'ing from common
implementations of the plugins.

Bug: 1109796
Change-Id: I9377b550acecb1411a63e1e87604f67c7b0732e4
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2670884
Commit-Queue: Daniel Hosseinian <dhoss@chromium.org>
Reviewed-by: K. Moon <kmoon@chromium.org>
Cr-Commit-Position: refs/heads/master@{#851827}

pdf/out_of_process_instance.cc

@@ -1124,6 +1124,10 @@ void OutOfProcessInstance::DidOpenPreview(std::unique_ptr<UrlLoader> loader,
   }
 }
 
+void OutOfProcessInstance::SendMessage(base::Value message) {
+  PostMessage(VarFromValue(message));
+}
+
 void OutOfProcessInstance::InitImageData(const gfx::Size& size) {
   pepper_image_data_ =
       pp::ImageData(this, PP_IMAGEDATAFORMAT_BGRA_PREMUL, PPSizeFromSize(size),

pdf/out_of_process_instance.h

@@ -182,6 +182,7 @@ class OutOfProcessInstance : public PdfViewPluginBase,
   void DidOpen(std::unique_ptr<UrlLoader> loader, int32_t result) override;
   void DidOpenPreview(std::unique_ptr<UrlLoader> loader,
                       int32_t result) override;
+  void SendMessage(base::Value message) override;
   void InitImageData(const gfx::Size& size) override;
   void OnGeometryChanged(double old_zoom, float old_device_scale) override;
   Image GetPluginImageData() const override;

pdf/pdf_view_plugin_base.h

@@ -92,6 +92,11 @@ class PdfViewPluginBase : public PDFEngine::Client,
   // Handles `postMessage()` calls from the embedder.
   void HandleMessage(const base::Value& message);
 
+  // Enqueues a "message" event carrying `message` to the embedder. Messages are
+  // guaranteed to be received in the order that they are sent. This method is
+  // non-blocking.
+  virtual void SendMessage(base::Value message) = 0;
+
   // Initialize image buffer(s) according to the new context size.
   virtual void InitImageData(const gfx::Size& size) = 0;
 

pdf/pdf_view_web_plugin.cc

@@ -400,6 +400,10 @@ void PdfViewWebPlugin::DidOpenPreview(std::unique_ptr<UrlLoader> loader,
   NOTIMPLEMENTED();
 }
 
+void PdfViewWebPlugin::SendMessage(base::Value message) {
+  post_message_sender_.Post(std::move(message));
+}
+
 void PdfViewWebPlugin::InitImageData(const gfx::Size& size) {
   mutable_image_data() = CreateN32PremulSkBitmap(gfx::SizeToSkISize(size));
 }

pdf/pdf_view_web_plugin.h

@@ -136,6 +136,7 @@ class PdfViewWebPlugin final : public PdfViewPluginBase,
   void DidOpen(std::unique_ptr<UrlLoader> loader, int32_t result) override;
   void DidOpenPreview(std::unique_ptr<UrlLoader> loader,
                       int32_t result) override;
+  void SendMessage(base::Value message) override;
   void InitImageData(const gfx::Size& size) override;
   void OnGeometryChanged(double old_zoom, float old_device_scale) override;