Use StringPiece for WebUI arguments that are usually literals

Constructs fewer strings and emits less code (~88KiB saved on an
official Linux build).

Change-Id: Ie97f4cd3ec991b4ba293735382d9f8bd2b9f3245
Reviewed-on: https://chromium-review.googlesource.com/986504
Reviewed-by: John Abd-El-Malek <jam@chromium.org>
Commit-Queue: Daniel Cheng <dcheng@chromium.org>
Cr-Commit-Position: refs/heads/master@{#547162}

content/browser/webui/web_ui_data_source_impl.cc

@@ -112,24 +112,24 @@ WebUIDataSourceImpl::WebUIDataSourceImpl(const std::string& source_name)
 WebUIDataSourceImpl::~WebUIDataSourceImpl() {
 }
 
-void WebUIDataSourceImpl::AddString(const std::string& name,
+void WebUIDataSourceImpl::AddString(base::StringPiece name,
                                     const base::string16& value) {
   // TODO(dschuyler): Share only one copy of these strings.
   localized_strings_.SetKey(name, base::Value(value));
-  replacements_[name] = base::UTF16ToUTF8(value);
+  replacements_[name.as_string()] = base::UTF16ToUTF8(value);
 }
 
-void WebUIDataSourceImpl::AddString(const std::string& name,
+void WebUIDataSourceImpl::AddString(base::StringPiece name,
                                     const std::string& value) {
   localized_strings_.SetKey(name, base::Value(value));
-  replacements_[name] = value;
+  replacements_[name.as_string()] = value;
 }
 
-void WebUIDataSourceImpl::AddLocalizedString(const std::string& name, int ids) {
+void WebUIDataSourceImpl::AddLocalizedString(base::StringPiece name, int ids) {
   std::string utf8_str =
       base::UTF16ToUTF8(GetContentClient()->GetLocalizedString(ids));
   localized_strings_.SetKey(name, base::Value(utf8_str));
-  replacements_[name] = utf8_str;
+  replacements_[name.as_string()] = utf8_str;
 }
 
 void WebUIDataSourceImpl::AddLocalizedStrings(
@@ -139,7 +139,7 @@ void WebUIDataSourceImpl::AddLocalizedStrings(
                                               &replacements_);
 }
 
-void WebUIDataSourceImpl::AddBoolean(const std::string& name, bool value) {
+void WebUIDataSourceImpl::AddBoolean(base::StringPiece name, bool value) {
   localized_strings_.SetBoolean(name, value);
   // TODO(dschuyler): Change name of |localized_strings_| to |load_time_data_|
   // or similar. These values haven't been found as strings for
@@ -148,21 +148,21 @@ void WebUIDataSourceImpl::AddBoolean(const std::string& name, bool value) {
   // replacements.
 }
 
-void WebUIDataSourceImpl::AddInteger(const std::string& name, int32_t value) {
+void WebUIDataSourceImpl::AddInteger(base::StringPiece name, int32_t value) {
   localized_strings_.SetInteger(name, value);
 }
 
-void WebUIDataSourceImpl::SetJsonPath(const std::string& path) {
+void WebUIDataSourceImpl::SetJsonPath(base::StringPiece path) {
   DCHECK(json_path_.empty());
   DCHECK(!path.empty());
 
-  json_path_ = path;
+  json_path_ = path.as_string();
   excluded_paths_.insert(json_path_);
 }
 
-void WebUIDataSourceImpl::AddResourcePath(const std::string &path,
+void WebUIDataSourceImpl::AddResourcePath(base::StringPiece path,
                                           int resource_id) {
-  path_to_idr_map_[path] = resource_id;
+  path_to_idr_map_[path.as_string()] = resource_id;
 }
 
 void WebUIDataSourceImpl::SetDefaultResource(int resource_id) {

content/browser/webui/web_ui_data_source_impl.h

@@ -30,15 +30,15 @@ class CONTENT_EXPORT WebUIDataSourceImpl : public URLDataSourceImpl,
                                            public WebUIDataSource {
  public:
   // WebUIDataSource implementation:
-  void AddString(const std::string& name, const base::string16& value) override;
-  void AddString(const std::string& name, const std::string& value) override;
-  void AddLocalizedString(const std::string& name, int ids) override;
+  void AddString(base::StringPiece name, const base::string16& value) override;
+  void AddString(base::StringPiece name, const std::string& value) override;
+  void AddLocalizedString(base::StringPiece name, int ids) override;
   void AddLocalizedStrings(
       const base::DictionaryValue& localized_strings) override;
-  void AddBoolean(const std::string& name, bool value) override;
-  void AddInteger(const std::string& name, int32_t value) override;
-  void SetJsonPath(const std::string& path) override;
-  void AddResourcePath(const std::string& path, int resource_id) override;
+  void AddBoolean(base::StringPiece name, bool value) override;
+  void AddInteger(base::StringPiece name, int32_t value) override;
+  void SetJsonPath(base::StringPiece path) override;
+  void AddResourcePath(base::StringPiece path, int resource_id) override;
   void SetDefaultResource(int resource_id) override;
   void SetRequestFilter(
       const WebUIDataSource::HandleRequestCallback& callback) override;

content/browser/webui/web_ui_impl.cc

@@ -239,9 +239,9 @@ void WebUIImpl::CallJavascriptFunctionUnsafe(
   ExecuteJavascript(GetJavascriptCall(function_name, args));
 }
 
-void WebUIImpl::RegisterMessageCallback(const std::string &message,
+void WebUIImpl::RegisterMessageCallback(base::StringPiece message,
                                         const MessageCallback& callback) {
-  message_callbacks_.insert(std::make_pair(message, callback));
+  message_callbacks_.emplace(message, callback);
 }
 
 void WebUIImpl::ProcessWebUIMessage(const GURL& source_url,

content/browser/webui/web_ui_impl.h

@@ -51,7 +51,7 @@ class CONTENT_EXPORT WebUIImpl : public WebUI,
   int GetBindings() const override;
   void SetBindings(int bindings) override;
   void AddMessageHandler(std::unique_ptr<WebUIMessageHandler> handler) override;
-  void RegisterMessageCallback(const std::string& message,
+  void RegisterMessageCallback(base::StringPiece message,
                                const MessageCallback& callback) override;
   void ProcessWebUIMessage(const GURL& source_url,
                            const std::string& message,

content/public/browser/web_ui.h

@@ -9,6 +9,7 @@
 
 #include "base/callback.h"
 #include "base/strings/string16.h"
+#include "base/strings/string_piece.h"
 #include "content/common/content_export.h"
 #include "ui/base/page_transition_types.h"
 
@@ -72,7 +73,7 @@ class CONTENT_EXPORT WebUI {
   // Used by WebUIMessageHandlers. If the given message is already registered,
   // the call has no effect.
   using MessageCallback = base::RepeatingCallback<void(const base::ListValue*)>;
-  virtual void RegisterMessageCallback(const std::string& message,
+  virtual void RegisterMessageCallback(base::StringPiece message,
                                        const MessageCallback& callback) = 0;
 
   // This is only needed if an embedder overrides handling of a WebUIMessage and

content/public/browser/web_ui_data_source.h

@@ -13,6 +13,7 @@
 
 #include "base/callback.h"
 #include "base/strings/string16.h"
+#include "base/strings/string_piece.h"
 #include "content/common/content_export.h"
 
 namespace base {
@@ -44,33 +45,33 @@ class WebUIDataSource {
       std::unique_ptr<base::DictionaryValue> update);
 
   // Adds a string keyed to its name to our dictionary.
-  virtual void AddString(const std::string& name,
+  virtual void AddString(base::StringPiece name,
                          const base::string16& value) = 0;
 
   // Adds a string keyed to its name to our dictionary.
-  virtual void AddString(const std::string& name, const std::string& value) = 0;
+  virtual void AddString(base::StringPiece name, const std::string& value) = 0;
 
   // Adds a localized string with resource |ids| keyed to its name to our
   // dictionary.
-  virtual void AddLocalizedString(const std::string& name, int ids) = 0;
+  virtual void AddLocalizedString(base::StringPiece name, int ids) = 0;
 
   // Add strings from |localized_strings| to our dictionary.
   virtual void AddLocalizedStrings(
       const base::DictionaryValue& localized_strings) = 0;
 
   // Adds a boolean keyed to its name to our dictionary.
-  virtual void AddBoolean(const std::string& name, bool value) = 0;
+  virtual void AddBoolean(base::StringPiece name, bool value) = 0;
 
   // Adds a signed 32-bit integer keyed to its name to our dictionary. Larger
   // integers may not be exactly representable in JavaScript. See
   // MAX_SAFE_INTEGER in /v8/src/globals.h.
-  virtual void AddInteger(const std::string& name, int32_t value) = 0;
+  virtual void AddInteger(base::StringPiece name, int32_t value) = 0;
 
   // Sets the path which will return the JSON strings.
-  virtual void SetJsonPath(const std::string& path) = 0;
+  virtual void SetJsonPath(base::StringPiece path) = 0;
 
   // Adds a mapping between a path name and a resource to return.
-  virtual void AddResourcePath(const std::string& path, int resource_id) = 0;
+  virtual void AddResourcePath(base::StringPiece path, int resource_id) = 0;
 
   // Sets the resource to returned when no other paths match.
   virtual void SetDefaultResource(int resource_id) = 0;

content/public/test/test_web_ui.h

@@ -35,7 +35,7 @@ class TestWebUI : public WebUI {
   int GetBindings() const override;
   void SetBindings(int bindings) override {}
   void AddMessageHandler(std::unique_ptr<WebUIMessageHandler> handler) override;
-  void RegisterMessageCallback(const std::string& message,
+  void RegisterMessageCallback(base::StringPiece message,
                                const MessageCallback& callback) override {}
   void ProcessWebUIMessage(const GURL& source_url,
                            const std::string& message,