Plugin Power Saver: Make PPS work well with prerendered pages.

chrome/renderer/plugins/chrome_plugin_placeholder.cc

 // Copyright 2013 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.
 
 #include "chrome/renderer/plugins/chrome_plugin_placeholder.h"
 
 #include "base/strings/string_number_conversions.h"
 #include "base/strings/utf_string_conversions.h"
 #include "base/values.h"
 #include "chrome/common/prerender_messages.h"
 #include "chrome/common/render_messages.h"
 #include "chrome/grit/generated_resources.h"
 #include "chrome/grit/renderer_resources.h"
 #include "chrome/renderer/chrome_content_renderer_client.h"
 #include "chrome/renderer/custom_menu_commands.h"
+#include "chrome/renderer/plugins/plugin_preroller.h"
 #include "chrome/renderer/plugins/plugin_uma.h"
 #include "components/content_settings/content/common/content_settings_messages.h"
 #include "content/app/strings/grit/content_strings.h"
 #include "content/public/common/context_menu_params.h"
 #include "content/public/renderer/render_frame.h"
 #include "content/public/renderer/render_thread.h"
 #include "gin/object_template_builder.h"
 #include "third_party/WebKit/public/web/WebDocument.h"
 #include "third_party/WebKit/public/web/WebInputEvent.h"
 #include "third_party/WebKit/public/web/WebLocalFrame.h"
@@ skipping 333 matching lines @@
   params.custom_items.push_back(hide_item);
 
   params.x = event.windowX;
   params.y = event.windowY;
 
   context_menu_request_id_ = render_frame()->ShowContextMenu(this, params);
   g_last_active_menu = this;
 #endif  // OS_ANDROID
 }
 
+blink::WebPlugin* ChromePluginPlaceholder::CreatePlugin() {
+  scoped_ptr<content::PluginInstanceThrottler> throttler;
+#if defined(ENABLE_PLUGINS)
+  // If the plugin has already been marked essential in its placeholder form,
+  // we shouldn't create a new throttler and start the process all over again.
+  if (power_saver_enabled()) {
+    throttler = content::PluginInstanceThrottler::Create();
+    // PluginPreroller manages its own lifetime.
+    new PluginPreroller(render_frame(), GetFrame(), GetPluginParams(),
+                        GetPluginInfo(), GetIdentifier(), title_,
+                        l10n_util::GetStringFUTF16(IDS_PLUGIN_BLOCKED, title_),
+                        throttler.get());
+  }
+#endif
+  return render_frame()->CreatePlugin(GetFrame(), GetPluginInfo(),
+                                      GetPluginParams(), throttler.Pass());
+}
+
 gin::ObjectTemplateBuilder ChromePluginPlaceholder::GetObjectTemplateBuilder(
     v8::Isolate* isolate) {
   return LoadablePluginPlaceholder::GetObjectTemplateBuilder(isolate).SetMethod(
       "openAboutPlugins", &ChromePluginPlaceholder::OpenAboutPluginsCallback);
 }