Reland: Plugin Placeholders: Refactor for platforms that don't support plugins

This patch removes a lot of plugin placeholder code from builds that don't support plugins (enable_plugins==0).

This is a reland of https://codereview.chromium.org/1126073003/.

See patchsets for fixes of the crashes.

BUG=493889
TBR=

Review URL: https://codereview.chromium.org/1161923004

Cr-Commit-Position: refs/heads/master@{#334054}

27 files changed, 455 insertions, 479 deletions

diff --git a/chrome/chrome_renderer.gypi b/chrome/chrome_renderer.gypi
index 2945b6a..73b86fe 100644
--- a/chrome/chrome_renderer.gypi
+++ b/chrome/chrome_renderer.gypi
@@ -36,8 +36,8 @@
       'renderer/net_benchmarking_extension.h',
       'renderer/page_load_histograms.cc',
       'renderer/page_load_histograms.h',
-      'renderer/plugins/chrome_plugin_placeholder.cc',
-      'renderer/plugins/chrome_plugin_placeholder.h',
+      'renderer/plugins/non_loadable_plugin_placeholder.cc',
+      'renderer/plugins/non_loadable_plugin_placeholder.h',
       'renderer/plugins/plugin_uma.cc',
       'renderer/plugins/plugin_uma.h',
       'renderer/plugins/shadow_dom_plugin_placeholder.cc',
@@ -182,6 +182,8 @@
       'renderer/pepper/pepper_shared_memory_message_filter.h',
       'renderer/pepper/pepper_uma_host.cc',
       'renderer/pepper/pepper_uma_host.h',
+      'renderer/plugins/chrome_plugin_placeholder.cc',
+      'renderer/plugins/chrome_plugin_placeholder.h',
       'renderer/plugins/plugin_preroller.cc',
       'renderer/plugins/plugin_preroller.h',
     ],
diff --git a/chrome/renderer/chrome_content_renderer_client.cc b/chrome/renderer/chrome_content_renderer_client.cc
index 59de107..258817d 100644
--- a/chrome/renderer/chrome_content_renderer_client.cc
+++ b/chrome/renderer/chrome_content_renderer_client.cc
@@ -40,7 +40,7 @@
 #include "chrome/renderer/net_benchmarking_extension.h"
 #include "chrome/renderer/page_load_histograms.h"
 #include "chrome/renderer/pepper/pepper_helper.h"
-#include "chrome/renderer/plugins/chrome_plugin_placeholder.h"
+#include "chrome/renderer/plugins/non_loadable_plugin_placeholder.h"
 #include "chrome/renderer/plugins/plugin_preroller.h"
 #include "chrome/renderer/plugins/plugin_uma.h"
 #include "chrome/renderer/plugins/shadow_dom_plugin_placeholder.h"
@@ -132,6 +132,10 @@
 #include "chrome/common/external_ipc_dumper.h"
 #endif
 
+#if defined(ENABLE_PLUGINS)
+#include "chrome/renderer/plugins/chrome_plugin_placeholder.h"
+#endif
+
 #if defined(ENABLE_PRINTING)
 #include "chrome/renderer/printing/chrome_print_web_view_helper_delegate.h"
 #include "components/printing/renderer/print_web_view_helper.h"
@@ -196,6 +200,7 @@ const char* const kPredefinedAllowedCompositorOrigins[] = {
 };
 #endif
 
+#if defined(ENABLE_PLUGINS)
 void AppendParams(const std::vector<base::string16>& additional_names,
                   const std::vector<base::string16>& additional_values,
                   WebVector<WebString>* existing_names,
@@ -223,26 +228,6 @@ void AppendParams(const std::vector<base::string16>& additional_names,
   existing_values->swap(values);
 }
 
-#if defined(ENABLE_SPELLCHECK)
-class SpellCheckReplacer : public content::RenderViewVisitor {
- public:
-  explicit SpellCheckReplacer(SpellCheck* spellcheck)
-      : spellcheck_(spellcheck) {}
-  bool Visit(content::RenderView* render_view) override;
-
- private:
-  SpellCheck* spellcheck_;  // New shared spellcheck for all views. Weak Ptr.
-  DISALLOW_COPY_AND_ASSIGN(SpellCheckReplacer);
-};
-
-bool SpellCheckReplacer::Visit(content::RenderView* render_view) {
-  SpellCheckProvider* provider = SpellCheckProvider::Get(render_view);
-  DCHECK(provider);
-  provider->set_spellcheck(spellcheck_);
-  return true;
-}
-#endif
-
 // For certain sandboxed Pepper plugins, use the JavaScript Content Settings.
 bool ShouldUseJavaScriptSettingForPlugin(const WebPluginInfo& plugin) {
   if (plugin.type != WebPluginInfo::PLUGIN_TYPE_PEPPER_IN_PROCESS &&
@@ -266,6 +251,27 @@ bool ShouldUseJavaScriptSettingForPlugin(const WebPluginInfo& plugin) {
 
   return false;
 }
+#endif  // defined(ENABLE_PLUGINS)
+
+#if defined(ENABLE_SPELLCHECK)
+class SpellCheckReplacer : public content::RenderViewVisitor {
+ public:
+  explicit SpellCheckReplacer(SpellCheck* spellcheck)
+      : spellcheck_(spellcheck) {}
+  bool Visit(content::RenderView* render_view) override;
+
+ private:
+  SpellCheck* spellcheck_;  // New shared spellcheck for all views. Weak Ptr.
+  DISALLOW_COPY_AND_ASSIGN(SpellCheckReplacer);
+};
+
+bool SpellCheckReplacer::Visit(content::RenderView* render_view) {
+  SpellCheckProvider* provider = SpellCheckProvider::Get(render_view);
+  DCHECK(provider);
+  provider->set_spellcheck(spellcheck_);
+  return true;
+}
+#endif
 
 #if defined(ENABLE_EXTENSIONS)
 void IsGuestViewApiAvailableToScriptContext(
@@ -650,25 +656,39 @@ bool ChromeContentRendererClient::OverrideCreatePlugin(
   }
 #endif
 
-  ChromeViewHostMsg_GetPluginInfo_Output output;
+  GURL url(params.url);
 #if defined(ENABLE_PLUGINS)
+  ChromeViewHostMsg_GetPluginInfo_Output output;
   render_frame->Send(new ChromeViewHostMsg_GetPluginInfo(
-      render_frame->GetRoutingID(), GURL(params.url),
-      frame->top()->document().url(), orig_mime_type, &output));
-
-#else
-  output.status = ChromeViewHostMsg_GetPluginInfo_Status::kNotFound;
-#endif
+      render_frame->GetRoutingID(), url, frame->top()->document().url(),
+      orig_mime_type, &output));
   *plugin = CreatePlugin(render_frame, frame, params, output);
+#else  // !defined(ENABLE_PLUGINS)
+
+#if defined(OS_ANDROID)
+  if (plugins::MobileYouTubePlugin::IsYouTubeURL(url, orig_mime_type)) {
+    base::StringPiece template_html(
+        ResourceBundle::GetSharedInstance().GetRawDataResource(
+            IDR_MOBILE_YOUTUBE_PLUGIN_HTML));
+    *plugin = (new plugins::MobileYouTubePlugin(render_frame, frame, params,
+                                                template_html))->plugin();
+    return true;
+  }
+#endif  // defined(OS_ANDROID)
+
+  PluginUMAReporter::GetInstance()->ReportPluginMissing(orig_mime_type, url);
+  *plugin = NonLoadablePluginPlaceholder::CreateNotSupportedPlugin(
+                render_frame, frame, params)->plugin();
+
+#endif  // defined(ENABLE_PLUGINS)
   return true;
 }
 
 WebPlugin* ChromeContentRendererClient::CreatePluginReplacement(
     content::RenderFrame* render_frame,
     const base::FilePath& plugin_path) {
-  ChromePluginPlaceholder* placeholder =
-      ChromePluginPlaceholder::CreateErrorPlugin(render_frame, plugin_path);
-  return placeholder->plugin();
+  return NonLoadablePluginPlaceholder::CreateErrorPlugin(render_frame,
+                                                         plugin_path)->plugin();
 }
 
 void ChromeContentRendererClient::DeferMediaLoad(
@@ -689,6 +709,7 @@ void ChromeContentRendererClient::DeferMediaLoad(
 #endif
 }
 
+#if defined(ENABLE_PLUGINS)
 WebPlugin* ChromeContentRendererClient::CreatePlugin(
     content::RenderFrame* render_frame,
     blink::WebLocalFrame* frame,
@@ -708,22 +729,8 @@ WebPlugin* ChromeContentRendererClient::CreatePlugin(
   // OverrideCreatePlugin.
   if (status == ChromeViewHostMsg_GetPluginInfo_Status::kNotFound ||
       orig_mime_type == content::kBrowserPluginMimeType) {
-#if defined(OS_ANDROID)
-    if (plugins::MobileYouTubePlugin::IsYouTubeURL(url, orig_mime_type)) {
-      base::StringPiece template_html(
-          ResourceBundle::GetSharedInstance().GetRawDataResource(
-              IDR_MOBILE_YOUTUBE_PLUGIN_HTML));
-      return (new plugins::MobileYouTubePlugin(
-                  render_frame,
-                  frame,
-                  original_params,
-                  template_html,
-                  GURL(ChromePluginPlaceholder::kPluginPlaceholderDataURL)))
-          ->plugin();
-    }
-#endif
     PluginUMAReporter::GetInstance()->ReportPluginMissing(orig_mime_type, url);
-    placeholder = ChromePluginPlaceholder::CreateMissingPlugin(
+    placeholder = ChromePluginPlaceholder::CreateLoadableMissingPlugin(
         render_frame, frame, original_params);
   } else {
     // TODO(bauerb): This should be in content/.
@@ -846,7 +853,6 @@ WebPlugin* ChromeContentRendererClient::CreatePlugin(
         }
 #endif  // !defined(DISABLE_NACL) && defined(ENABLE_EXTENSIONS)
 
-#if defined(ENABLE_PLUGINS)
         // Delay loading plugins if prerendering.
         // TODO(mmenke):  In the case of prerendering, feed into
         //                ChromeContentRendererClient::CreatePlugin instead, to
@@ -881,7 +887,6 @@ WebPlugin* ChromeContentRendererClient::CreatePlugin(
               blocked_for_background_tab);
           placeholder->set_blocked_for_prerendering(is_prerendering);
           placeholder->set_power_saver_enabled(power_saver_enabled);
-          placeholder->set_allow_loading(true);
           break;
         }
 
@@ -897,9 +902,6 @@ WebPlugin* ChromeContentRendererClient::CreatePlugin(
 
         return render_frame->CreatePlugin(frame, info, params,
                                           throttler.Pass());
-#else   // !defined(ENABLE_PLUGINS)
-        return render_frame->CreatePlugin(frame, info, params, nullptr);
-#endif  // defined(ENABLE_PLUGINS)
       }
       case ChromeViewHostMsg_GetPluginInfo_Status::kNPAPINotSupported: {
         RenderThread::Get()->RecordAction(
@@ -924,7 +926,6 @@ WebPlugin* ChromeContentRendererClient::CreatePlugin(
         placeholder = create_blocked_plugin(
             IDR_BLOCKED_PLUGIN_HTML,
             l10n_util::GetStringFUTF16(IDS_PLUGIN_OUTDATED, group_name));
-        placeholder->set_allow_loading(true);
         render_frame->Send(new ChromeViewHostMsg_BlockedOutdatedPlugin(
             render_frame->GetRoutingID(), placeholder->CreateRoutingId(),
             identifier));
@@ -943,7 +944,6 @@ WebPlugin* ChromeContentRendererClient::CreatePlugin(
         placeholder = create_blocked_plugin(
             IDR_BLOCKED_PLUGIN_HTML,
             l10n_util::GetStringFUTF16(IDS_PLUGIN_NOT_AUTHORIZED, group_name));
-        placeholder->set_allow_loading(true);
         if (info.type != content::WebPluginInfo::PLUGIN_TYPE_NPAPI) {
           render_frame->Send(new ChromeViewHostMsg_BlockedUnauthorizedPlugin(
               render_frame->GetRoutingID(),
@@ -957,7 +957,6 @@ WebPlugin* ChromeContentRendererClient::CreatePlugin(
         placeholder = create_blocked_plugin(
             IDR_BLOCKED_PLUGIN_HTML,
             l10n_util::GetStringFUTF16(IDS_PLUGIN_BLOCKED, group_name));
-        placeholder->set_allow_loading(true);
         RenderThread::Get()->RecordAction(UserMetricsAction("Plugin_Blocked"));
         observer->DidBlockContentType(content_type, group_name);
         break;
@@ -967,7 +966,7 @@ WebPlugin* ChromeContentRendererClient::CreatePlugin(
             IDR_BLOCKED_PLUGIN_HTML,
             l10n_util::GetStringFUTF16(IDS_PLUGIN_BLOCKED_BY_POLICY,
                                        group_name));
-        placeholder->set_allow_loading(false);
+        placeholder->DisallowLoading();
         RenderThread::Get()->RecordAction(
             UserMetricsAction("Plugin_BlockedByPolicy"));
         observer->DidBlockContentType(content_type, group_name);
@@ -978,6 +977,7 @@ WebPlugin* ChromeContentRendererClient::CreatePlugin(
   placeholder->SetStatus(status);
   return placeholder->plugin();
 }
+#endif  // defined(ENABLE_PLUGINS)
 
 // For NaCl content handling plugins, the NaCl manifest is stored in an
 // additonal 'nacl' param associated with the MIME type.
diff --git a/chrome/renderer/chrome_content_renderer_client.h b/chrome/renderer/chrome_content_renderer_client.h
index 952e879..93fe153 100644
--- a/chrome/renderer/chrome_content_renderer_client.h
+++ b/chrome/renderer/chrome_content_renderer_client.h
@@ -168,11 +168,13 @@ class ChromeContentRendererClient : public content::ContentRendererClient {
   void SetSpellcheck(SpellCheck* spellcheck);
 #endif
 
+#if defined(ENABLE_PLUGINS)
   static blink::WebPlugin* CreatePlugin(
       content::RenderFrame* render_frame,
       blink::WebLocalFrame* frame,
       const blink::WebPluginParams& params,
       const ChromeViewHostMsg_GetPluginInfo_Output& output);
+#endif
 
 #if defined(ENABLE_PLUGINS) && defined(ENABLE_EXTENSIONS)
   static bool IsExtensionOrSharedModuleWhitelisted(
diff --git a/chrome/renderer/plugins/chrome_plugin_placeholder.cc b/chrome/renderer/plugins/chrome_plugin_placeholder.cc
index 402bfb6..165eebb 100644
--- a/chrome/renderer/plugins/chrome_plugin_placeholder.cc
+++ b/chrome/renderer/plugins/chrome_plugin_placeholder.cc
@@ -16,7 +16,6 @@
 #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"
@@ -45,13 +44,11 @@ using content::RenderThread;
 using content::RenderView;
 
 namespace {
-const plugins::PluginPlaceholder* g_last_active_menu = NULL;
+const ChromePluginPlaceholder* g_last_active_menu = NULL;
 }  // namespace
 
-// The placeholder is loaded in normal web renderer processes, so it should not
-// have a chrome:// scheme that might let it be confused with a WebUI page.
-const char ChromePluginPlaceholder::kPluginPlaceholderDataURL[] =
-    "data:text/html,pluginplaceholderdata";
+gin::WrapperInfo ChromePluginPlaceholder::kWrapperInfo = {
+    gin::kEmbedderNativeGin};
 
 ChromePluginPlaceholder::ChromePluginPlaceholder(
     content::RenderFrame* render_frame,
@@ -62,8 +59,7 @@ ChromePluginPlaceholder::ChromePluginPlaceholder(
     : plugins::LoadablePluginPlaceholder(render_frame,
                                          frame,
                                          params,
-                                         html_data,
-                                         GURL(kPluginPlaceholderDataURL)),
+                                         html_data),
       status_(ChromeViewHostMsg_GetPluginInfo_Status::kAllowed),
       title_(title),
 #if defined(ENABLE_PLUGIN_INSTALLATION)
@@ -91,7 +87,7 @@ ChromePluginPlaceholder::~ChromePluginPlaceholder() {
 }
 
 // static
-ChromePluginPlaceholder* ChromePluginPlaceholder::CreateMissingPlugin(
+ChromePluginPlaceholder* ChromePluginPlaceholder::CreateLoadableMissingPlugin(
     content::RenderFrame* render_frame,
     WebLocalFrame* frame,
     const WebPluginParams& params) {
@@ -105,34 +101,9 @@ ChromePluginPlaceholder* ChromePluginPlaceholder::CreateMissingPlugin(
 
   std::string html_data = webui::GetI18nTemplateHtml(template_html, &values);
 
-  // |missing_plugin| will destroy itself when its WebViewPlugin is going away.
-  ChromePluginPlaceholder* missing_plugin = new ChromePluginPlaceholder(
-      render_frame, frame, params, html_data, params.mimeType);
-  missing_plugin->set_allow_loading(true);
-  return missing_plugin;
-}
-
-// static
-ChromePluginPlaceholder* ChromePluginPlaceholder::CreateErrorPlugin(
-    content::RenderFrame* render_frame,
-    const base::FilePath& file_path) {
-  base::DictionaryValue values;
-  values.SetString("message",
-                   l10n_util::GetStringUTF8(IDS_PLUGIN_INITIALIZATION_ERROR));
-
-  const base::StringPiece template_html(
-      ResourceBundle::GetSharedInstance().GetRawDataResource(
-          IDR_BLOCKED_PLUGIN_HTML));
-  std::string html_data = webui::GetI18nTemplateHtml(template_html, &values);
-
-  WebPluginParams params;
-  // |missing_plugin| will destroy itself when its WebViewPlugin is going away.
-  ChromePluginPlaceholder* plugin = new ChromePluginPlaceholder(
-      render_frame, NULL, params, html_data, params.mimeType);
-
-  RenderThread::Get()->Send(new ChromeViewHostMsg_CouldNotLoadPlugin(
-      plugin->routing_id(), file_path));
-  return plugin;
+  // Will destroy itself when its WebViewPlugin is going away.
+  return new ChromePluginPlaceholder(render_frame, frame, params, html_data,
+                                     params.mimeType);
 }
 
 // static
@@ -176,10 +147,8 @@ ChromePluginPlaceholder* ChromePluginPlaceholder::CreateBlockedPlugin(
   ChromePluginPlaceholder* blocked_plugin = new ChromePluginPlaceholder(
       render_frame, frame, params, html_data, name);
 
-#if defined(ENABLE_PLUGINS)
   if (!poster_info.poster_attribute.empty())
     blocked_plugin->BlockForPowerSaverPoster();
-#endif
   blocked_plugin->SetPluginInfo(info);
   blocked_plugin->SetIdentifier(identifier);
   return blocked_plugin;
@@ -305,10 +274,8 @@ void ChromePluginPlaceholder::OnMenuAction(int request_id, unsigned action) {
   switch (action) {
     case chrome::MENU_COMMAND_PLUGIN_RUN: {
       RenderThread::Get()->RecordAction(UserMetricsAction("Plugin_Load_Menu"));
-#if defined(ENABLE_PLUGINS)
       MarkPluginEssential(
           content::PluginInstanceThrottler::UNTHROTTLE_METHOD_BY_CLICK);
-#endif
       LoadPlugin();
       break;
     }
@@ -327,8 +294,12 @@ void ChromePluginPlaceholder::OnMenuClosed(int request_id) {
   context_menu_request_id_ = 0;
 }
 
+v8::Local<v8::Value> ChromePluginPlaceholder::GetV8Handle(
+    v8::Isolate* isolate) {
+  return gin::CreateHandle(isolate, this).ToV8();
+}
+
 void ChromePluginPlaceholder::ShowContextMenu(const WebMouseEvent& event) {
-#if !defined(OS_ANDROID)  // The context menu is not applicable on Android.
   if (context_menu_request_id_)
     return;  // Don't allow nested context menu requests.
 
@@ -364,12 +335,10 @@ void ChromePluginPlaceholder::ShowContextMenu(const WebMouseEvent& event) {
 
   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()) {
@@ -380,13 +349,21 @@ blink::WebPlugin* ChromePluginPlaceholder::CreatePlugin() {
                         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);
+  return gin::Wrappable<ChromePluginPlaceholder>::GetObjectTemplateBuilder(
+             isolate)
+      .SetMethod<void (ChromePluginPlaceholder::*)()>(
+           "hide", &ChromePluginPlaceholder::HideCallback)
+      .SetMethod<void (ChromePluginPlaceholder::*)()>(
+           "load", &ChromePluginPlaceholder::LoadCallback)
+      .SetMethod<void (ChromePluginPlaceholder::*)()>(
+           "didFinishLoading",
+           &ChromePluginPlaceholder::DidFinishLoadingCallback)
+      .SetMethod("openAboutPlugins",
+                 &ChromePluginPlaceholder::OpenAboutPluginsCallback);
 }
diff --git a/chrome/renderer/plugins/chrome_plugin_placeholder.h b/chrome/renderer/plugins/chrome_plugin_placeholder.h
index d5fb2f9..85d49b7 100644
--- a/chrome/renderer/plugins/chrome_plugin_placeholder.h
+++ b/chrome/renderer/plugins/chrome_plugin_placeholder.h
@@ -28,11 +28,13 @@ struct PlaceholderPosterInfo {
   gfx::Size custom_poster_size;
 };
 
-class ChromePluginPlaceholder : public plugins::LoadablePluginPlaceholder,
-                                public content::RenderProcessObserver,
-                                public content::ContextMenuClient {
+class ChromePluginPlaceholder final
+    : public plugins::LoadablePluginPlaceholder,
+      public content::RenderProcessObserver,
+      public content::ContextMenuClient,
+      public gin::Wrappable<ChromePluginPlaceholder> {
  public:
-  static const char kPluginPlaceholderDataURL[];
+  static gin::WrapperInfo kWrapperInfo;
 
   static ChromePluginPlaceholder* CreateBlockedPlugin(
       content::RenderFrame* render_frame,
@@ -46,15 +48,11 @@ class ChromePluginPlaceholder : public plugins::LoadablePluginPlaceholder,
       const PlaceholderPosterInfo& poster_info);
 
   // Creates a new WebViewPlugin with a MissingPlugin as a delegate.
-  static ChromePluginPlaceholder* CreateMissingPlugin(
+  static ChromePluginPlaceholder* CreateLoadableMissingPlugin(
       content::RenderFrame* render_frame,
       blink::WebLocalFrame* frame,
       const blink::WebPluginParams& params);
 
-  static ChromePluginPlaceholder* CreateErrorPlugin(
-      content::RenderFrame* render_frame,
-      const base::FilePath& plugin_path);
-
   void SetStatus(ChromeViewHostMsg_GetPluginInfo_Status status);
 
 #if defined(ENABLE_PLUGIN_INSTALLATION)
@@ -74,12 +72,13 @@ class ChromePluginPlaceholder : public plugins::LoadablePluginPlaceholder,
 
   // gin::Wrappable (via PluginPlaceholder) method
   gin::ObjectTemplateBuilder GetObjectTemplateBuilder(
-      v8::Isolate* isolate) override;
+      v8::Isolate* isolate) final;
 
   // content::RenderViewObserver (via PluginPlaceholder) override:
   bool OnMessageReceived(const IPC::Message& message) override;
 
   // WebViewPlugin::Delegate (via PluginPlaceholder) methods:
+  v8::Local<v8::Value> GetV8Handle(v8::Isolate* isolate) override;
   void ShowContextMenu(const blink::WebMouseEvent&) override;
 
   // content::RenderProcessObserver methods:
diff --git a/chrome/renderer/plugins/non_loadable_plugin_placeholder.cc b/chrome/renderer/plugins/non_loadable_plugin_placeholder.cc
new file mode 100644
index 0000000..598ad16
--- /dev/null
+++ b/chrome/renderer/plugins/non_loadable_plugin_placeholder.cc
@@ -0,0 +1,60 @@
+// Copyright 2015 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/non_loadable_plugin_placeholder.h"
+
+#include "base/files/file_path.h"
+#include "base/values.h"
+#include "chrome/common/render_messages.h"
+#include "chrome/grit/generated_resources.h"
+#include "chrome/grit/renderer_resources.h"
+#include "components/plugins/renderer/plugin_placeholder.h"
+#include "content/app/strings/grit/content_strings.h"
+#include "content/public/renderer/render_thread.h"
+#include "ui/base/l10n/l10n_util.h"
+#include "ui/base/resource/resource_bundle.h"
+#include "ui/base/webui/jstemplate_builder.h"
+
+// static
+plugins::PluginPlaceholder*
+NonLoadablePluginPlaceholder::CreateNotSupportedPlugin(
+    content::RenderFrame* render_frame,
+    blink::WebLocalFrame* frame,
+    const blink::WebPluginParams& params) {
+  const base::StringPiece template_html(
+      ResourceBundle::GetSharedInstance().GetRawDataResource(
+          IDR_BLOCKED_PLUGIN_HTML));
+
+  base::DictionaryValue values;
+  values.SetString("message",
+                   l10n_util::GetStringUTF8(IDS_PLUGIN_NOT_SUPPORTED));
+
+  std::string html_data = webui::GetI18nTemplateHtml(template_html, &values);
+
+  // PluginPlaceholder will destroy itself when its WebViewPlugin is going away.
+  return new plugins::PluginPlaceholder(render_frame, frame, params, html_data);
+}
+
+// static
+plugins::PluginPlaceholder* NonLoadablePluginPlaceholder::CreateErrorPlugin(
+    content::RenderFrame* render_frame,
+    const base::FilePath& file_path) {
+  base::DictionaryValue values;
+  values.SetString("message",
+                   l10n_util::GetStringUTF8(IDS_PLUGIN_INITIALIZATION_ERROR));
+
+  const base::StringPiece template_html(
+      ResourceBundle::GetSharedInstance().GetRawDataResource(
+          IDR_BLOCKED_PLUGIN_HTML));
+  std::string html_data = webui::GetI18nTemplateHtml(template_html, &values);
+
+  blink::WebPluginParams params;
+  // PluginPlaceholder will destroy itself when its WebViewPlugin is going away.
+  plugins::PluginPlaceholder* plugin =
+      new plugins::PluginPlaceholder(render_frame, nullptr, params, html_data);
+
+  content::RenderThread::Get()->Send(new ChromeViewHostMsg_CouldNotLoadPlugin(
+      plugin->routing_id(), file_path));
+  return plugin;
+}
diff --git a/chrome/renderer/plugins/non_loadable_plugin_placeholder.h b/chrome/renderer/plugins/non_loadable_plugin_placeholder.h
new file mode 100644
index 0000000..e872e5e
--- /dev/null
+++ b/chrome/renderer/plugins/non_loadable_plugin_placeholder.h
@@ -0,0 +1,43 @@
+// Copyright 2015 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 CHROME_RENDERER_PLUGINS_NON_LOADABLE_PLUGIN_PLACEHOLDER_H_
+#define CHROME_RENDERER_PLUGINS_NON_LOADABLE_PLUGIN_PLACEHOLDER_H_
+
+#include "base/macros.h"
+
+namespace base {
+class FilePath;
+}
+
+namespace blink {
+class WebLocalFrame;
+struct WebPluginParams;
+}
+
+namespace content {
+class RenderFrame;
+}
+
+namespace plugins {
+class PluginPlaceholder;
+}
+
+class NonLoadablePluginPlaceholder {
+ public:
+  // Creates a non-loadable plugin placeholder for platforms without plugins.
+  static plugins::PluginPlaceholder* CreateNotSupportedPlugin(
+      content::RenderFrame* render_frame,
+      blink::WebLocalFrame* frame,
+      const blink::WebPluginParams& params);
+
+  static plugins::PluginPlaceholder* CreateErrorPlugin(
+      content::RenderFrame* render_frame,
+      const base::FilePath& file_path);
+
+ private:
+  DISALLOW_IMPLICIT_CONSTRUCTORS(NonLoadablePluginPlaceholder);
+};
+
+#endif  // CHROME_RENDERER_PLUGINS_NON_LOADABLE_PLUGIN_PLACEHOLDER_H_
diff --git a/chrome/renderer/plugins/plugin_preroller.cc b/chrome/renderer/plugins/plugin_preroller.cc
index 2d42f4e..6c27793 100644
--- a/chrome/renderer/plugins/plugin_preroller.cc
+++ b/chrome/renderer/plugins/plugin_preroller.cc
@@ -68,7 +68,6 @@ void PluginPreroller::OnThrottleStateChange() {
           IDR_PLUGIN_POSTER_HTML, message_, poster_info);
   placeholder->SetPremadePlugin(throttler_);
   placeholder->set_power_saver_enabled(true);
-  placeholder->set_allow_loading(true);
 
   blink::WebPluginContainer* container =
       throttler_->GetWebPlugin()->container();
diff --git a/chrome/renderer/resources/blocked_plugin.html b/chrome/renderer/resources/blocked_plugin.html
index 7a92c1d..0d4dc4a 100644
--- a/chrome/renderer/resources/blocked_plugin.html
+++ b/chrome/renderer/resources/blocked_plugin.html
@@ -3,10 +3,8 @@
 <head>
 <meta charset="utf-8">
 <meta name="viewport" content="width=device-width, user-scalable=no">
+<if expr="not is_android">
 <script>
-function debug(msg) {
-  document.getElementById('debug').textContent = msg;
-}
 function setMessage(msg) {
   document.getElementById('message').textContent = msg;
 }
@@ -15,6 +13,12 @@ function notifyDidFinishLoading() {
     plugin.didFinishLoading();
 }
 </script>
+</if>
+<if expr="is_android">
+<script>
+function notifyDidFinishLoading() {}
+</script>
+</if>
 <link rel="stylesheet" href="plugin_placeholders.css"></link>
 <style>
 body {
@@ -37,7 +41,6 @@ body {
   <img id="plugin_icon" src="plugin_blocked_android.png">
 </if>
 <h1 id="message" i18n-content="message"></h1>
-<p id="debug"> </p>
 </div>
 <div id="close" i18n-values="title:hide" onclick="plugin.hide();"></div>
 </div>
diff --git a/components/plugins.gypi b/components/plugins.gypi
index fde25c6..9061833 100644
--- a/components/plugins.gypi
+++ b/components/plugins.gypi
@@ -36,14 +36,19 @@
           ],
           'sources': [
             # Note: sources list duplicated in GN build.
-            'plugins/renderer/loadable_plugin_placeholder.cc',
-            'plugins/renderer/loadable_plugin_placeholder.h',
             'plugins/renderer/plugin_placeholder.cc',
             'plugins/renderer/plugin_placeholder.h',
             'plugins/renderer/webview_plugin.cc',
             'plugins/renderer/webview_plugin.h',
           ],
           'conditions' : [
+            ['enable_plugins==1', {
+              'sources': [
+                # Note: sources list duplicated in GN build.
+                'plugins/renderer/loadable_plugin_placeholder.cc',
+                'plugins/renderer/loadable_plugin_placeholder.h',
+              ]
+            }],
             ['OS=="android"', {
               'sources': [
                 # Note: sources list duplicated in GN build.
diff --git a/components/plugins/renderer/BUILD.gn b/components/plugins/renderer/BUILD.gn
index ef7e8f1..446ad99 100644
--- a/components/plugins/renderer/BUILD.gn
+++ b/components/plugins/renderer/BUILD.gn
@@ -2,15 +2,21 @@
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
+import("//build/config/features.gni")
+
 static_library("renderer") {
   sources = [
-    "loadable_plugin_placeholder.cc",
-    "loadable_plugin_placeholder.h",
     "plugin_placeholder.cc",
     "plugin_placeholder.h",
     "webview_plugin.cc",
     "webview_plugin.h",
   ]
+  if (enable_plugins) {
+    sources += [
+      "loadable_plugin_placeholder.cc",
+      "loadable_plugin_placeholder.h",
+    ]
+  }
   if (is_android) {
     sources += [
       "mobile_youtube_plugin.cc",
diff --git a/components/plugins/renderer/loadable_plugin_placeholder.cc b/components/plugins/renderer/loadable_plugin_placeholder.cc
index ea288e2..a41c9ea 100644
--- a/components/plugins/renderer/loadable_plugin_placeholder.cc
+++ b/components/plugins/renderer/loadable_plugin_placeholder.cc
@@ -9,7 +9,6 @@
 #include "base/command_line.h"
 #include "base/json/string_escape.h"
 #include "base/strings/string_piece.h"
-#include "base/strings/string_util.h"
 #include "base/strings/utf_string_conversions.h"
 #include "base/thread_task_runner_handle.h"
 #include "base/values.h"
@@ -29,24 +28,13 @@
 #include "third_party/WebKit/public/web/WebScriptSource.h"
 #include "third_party/WebKit/public/web/WebSerializedScriptValue.h"
 #include "third_party/WebKit/public/web/WebView.h"
-#include "third_party/re2/re2/re2.h"
 
 using base::UserMetricsAction;
-using blink::WebElement;
-using blink::WebLocalFrame;
-using blink::WebMouseEvent;
-using blink::WebNode;
-using blink::WebPlugin;
-using blink::WebPluginContainer;
-using blink::WebPluginParams;
-using blink::WebScriptSource;
-using blink::WebURLRequest;
 using content::PluginInstanceThrottler;
 using content::RenderThread;
 
 namespace plugins {
 
-#if defined(ENABLE_PLUGINS)
 // TODO(tommycli): After an unthrottling size update, re-check the size after
 // this delay, as Blink can report incorrect sizes to plugins while the
 // compositing state is dirty. Chosen because it seems to work.
@@ -69,26 +57,19 @@ void LoadablePluginPlaceholder::SetPremadePlugin(
   DCHECK(!premade_throttler_);
   premade_throttler_ = throttler;
 }
-#endif
 
 LoadablePluginPlaceholder::LoadablePluginPlaceholder(
     content::RenderFrame* render_frame,
-    WebLocalFrame* frame,
-    const WebPluginParams& params,
-    const std::string& html_data,
-    GURL placeholderDataUrl)
-    : PluginPlaceholder(render_frame,
-                        frame,
-                        params,
-                        html_data,
-                        placeholderDataUrl),
+    blink::WebLocalFrame* frame,
+    const blink::WebPluginParams& params,
+    const std::string& html_data)
+    : PluginPlaceholderBase(render_frame, frame, params, html_data),
       is_blocked_for_background_tab_(false),
       is_blocked_for_prerendering_(false),
       is_blocked_for_power_saver_poster_(false),
       power_saver_enabled_(false),
       premade_throttler_(nullptr),
-      allow_loading_(false),
-      hidden_(false),
+      allow_loading_(true),
       finished_loading_(false),
       in_size_recheck_(false),
       weak_factory_(this) {
@@ -97,7 +78,6 @@ LoadablePluginPlaceholder::LoadablePluginPlaceholder(
 LoadablePluginPlaceholder::~LoadablePluginPlaceholder() {
 }
 
-#if defined(ENABLE_PLUGINS)
 void LoadablePluginPlaceholder::MarkPluginEssential(
     PluginInstanceThrottler::PowerSaverUnthrottleMethod method) {
   if (!power_saver_enabled_)
@@ -116,39 +96,17 @@ void LoadablePluginPlaceholder::MarkPluginEssential(
       LoadPlugin();
   }
 }
-#endif
-
-void LoadablePluginPlaceholder::BindWebFrame(blink::WebFrame* frame) {
-  v8::Isolate* isolate = blink::mainThreadIsolate();
-  v8::HandleScope handle_scope(isolate);
-  v8::Local<v8::Context> context = frame->mainWorldScriptContext();
-  DCHECK(!context.IsEmpty());
-
-  v8::Context::Scope context_scope(context);
-  v8::Local<v8::Object> global = context->Global();
-  global->Set(gin::StringToV8(isolate, "plugin"),
-              gin::CreateHandle(isolate, this).ToV8());
-}
-
-gin::ObjectTemplateBuilder LoadablePluginPlaceholder::GetObjectTemplateBuilder(
-    v8::Isolate* isolate) {
-  return gin::Wrappable<PluginPlaceholder>::GetObjectTemplateBuilder(isolate)
-      .SetMethod("load", &LoadablePluginPlaceholder::LoadCallback)
-      .SetMethod("hide", &LoadablePluginPlaceholder::HideCallback)
-      .SetMethod("didFinishLoading",
-                 &LoadablePluginPlaceholder::DidFinishLoadingCallback);
-}
 
-void LoadablePluginPlaceholder::ReplacePlugin(WebPlugin* new_plugin) {
+void LoadablePluginPlaceholder::ReplacePlugin(blink::WebPlugin* new_plugin) {
   CHECK(plugin());
   if (!new_plugin)
     return;
-  WebPluginContainer* container = plugin()->container();
+  blink::WebPluginContainer* container = plugin()->container();
   // Set the new plugin on the container before initializing it.
   container->setPlugin(new_plugin);
   // Save the element in case the plugin is removed from the page during
   // initialization.
-  WebElement element = container->element();
+  blink::WebElement element = container->element();
   bool plugin_needs_initialization =
       !premade_throttler_ || new_plugin != premade_throttler_->GetWebPlugin();
   if (plugin_needs_initialization && !new_plugin->initialize(container)) {
@@ -176,54 +134,6 @@ void LoadablePluginPlaceholder::ReplacePlugin(WebPlugin* new_plugin) {
   plugin()->destroy();
 }
 
-void LoadablePluginPlaceholder::HidePlugin() {
-  hidden_ = true;
-  if (!plugin())
-    return;
-  WebPluginContainer* container = plugin()->container();
-  WebElement element = container->element();
-  element.setAttribute("style", "display: none;");
-  // If we have a width and height, search for a parent (often <div>) with the
-  // same dimensions. If we find such a parent, hide that as well.
-  // This makes much more uncovered page content usable (including clickable)
-  // as opposed to merely visible.
-  // TODO(cevans) -- it's a foul heuristic but we're going to tolerate it for
-  // now for these reasons:
-  // 1) Makes the user experience better.
-  // 2) Foulness is encapsulated within this single function.
-  // 3) Confidence in no fasle positives.
-  // 4) Seems to have a good / low false negative rate at this time.
-  if (element.hasAttribute("width") && element.hasAttribute("height")) {
-    std::string width_str("width:[\\s]*");
-    width_str += element.getAttribute("width").utf8().data();
-    if (EndsWith(width_str, "px", false)) {
-      width_str = width_str.substr(0, width_str.length() - 2);
-    }
-    base::TrimWhitespace(width_str, base::TRIM_TRAILING, &width_str);
-    width_str += "[\\s]*px";
-    std::string height_str("height:[\\s]*");
-    height_str += element.getAttribute("height").utf8().data();
-    if (EndsWith(height_str, "px", false)) {
-      height_str = height_str.substr(0, height_str.length() - 2);
-    }
-    base::TrimWhitespace(height_str, base::TRIM_TRAILING, &height_str);
-    height_str += "[\\s]*px";
-    WebNode parent = element;
-    while (!parent.parentNode().isNull()) {
-      parent = parent.parentNode();
-      if (!parent.isElementNode())
-        continue;
-      element = parent.toConst<WebElement>();
-      if (element.hasAttribute("style")) {
-        std::string style_str = element.getAttribute("style").utf8();
-        if (RE2::PartialMatch(style_str, width_str) &&
-            RE2::PartialMatch(style_str, height_str))
-          element.setAttribute("style", "display: none;");
-      }
-    }
-  }
-}
-
 void LoadablePluginPlaceholder::SetMessage(const base::string16& message) {
   message_ = message;
   if (finished_loading_)
@@ -236,11 +146,10 @@ void LoadablePluginPlaceholder::UpdateMessage() {
   std::string script =
       "window.setMessage(" + base::GetQuotedJSONString(message_) + ")";
   plugin()->web_view()->mainFrame()->executeScript(
-      WebScriptSource(base::UTF8ToUTF16(script)));
+      blink::WebScriptSource(base::UTF8ToUTF16(script)));
 }
 
 void LoadablePluginPlaceholder::PluginDestroyed() {
-#if defined(ENABLE_PLUGINS)
   if (power_saver_enabled_) {
     if (premade_throttler_) {
       // Since the premade plugin has been detached from the container, it will
@@ -256,23 +165,19 @@ void LoadablePluginPlaceholder::PluginDestroyed() {
     // Prevent processing subsequent calls to MarkPluginEssential.
     power_saver_enabled_ = false;
   }
-#endif
 
-  PluginPlaceholder::PluginDestroyed();
+  PluginPlaceholderBase::PluginDestroyed();
 }
 
 v8::Local<v8::Object> LoadablePluginPlaceholder::GetV8ScriptableObject(
     v8::Isolate* isolate) const {
-#if defined(ENABLE_PLUGINS)
   // Pass through JavaScript access to the underlying throttled plugin.
   if (premade_throttler_ && premade_throttler_->GetWebPlugin()) {
     return premade_throttler_->GetWebPlugin()->v8ScriptableObject(isolate);
   }
-#endif
   return v8::Local<v8::Object>();
 }
 
-#if defined(ENABLE_PLUGINS)
 void LoadablePluginPlaceholder::OnUnobscuredSizeUpdate(
     const gfx::Size& unobscured_size) {
   DCHECK(
@@ -304,7 +209,6 @@ void LoadablePluginPlaceholder::OnUnobscuredSizeUpdate(
     size_update_timer_.Stop();
   }
 }
-#endif  // defined(ENABLE_PLUGINS)
 
 void LoadablePluginPlaceholder::WasShown() {
   if (is_blocked_for_background_tab_) {
@@ -337,7 +241,7 @@ void LoadablePluginPlaceholder::OnSetIsPrerendering(bool is_prerendering) {
 void LoadablePluginPlaceholder::LoadPlugin() {
   // This is not strictly necessary but is an important defense in case the
   // event propagation changes between "close" vs. "click-to-play".
-  if (hidden_)
+  if (hidden())
     return;
   if (!plugin())
     return;
@@ -357,19 +261,12 @@ void LoadablePluginPlaceholder::LoadPlugin() {
 
 void LoadablePluginPlaceholder::LoadCallback() {
   RenderThread::Get()->RecordAction(UserMetricsAction("Plugin_Load_Click"));
-#if defined(ENABLE_PLUGINS)
   // If the user specifically clicks on the plugin content's placeholder,
   // disable power saver throttling for this instance.
   MarkPluginEssential(PluginInstanceThrottler::UNTHROTTLE_METHOD_BY_CLICK);
-#endif
   LoadPlugin();
 }
 
-void LoadablePluginPlaceholder::HideCallback() {
-  RenderThread::Get()->RecordAction(UserMetricsAction("Plugin_Hide_Click"));
-  HidePlugin();
-}
-
 void LoadablePluginPlaceholder::DidFinishLoadingCallback() {
   finished_loading_ = true;
   if (message_.length() > 0)
@@ -384,7 +281,7 @@ void LoadablePluginPlaceholder::DidFinishLoadingCallback() {
   // placeholder to be ready to receive simulated user input.
   if (base::CommandLine::ForCurrentProcess()->HasSwitch(
           switches::kEnablePluginPlaceholderTesting)) {
-    WebElement element = plugin()->container()->element();
+    blink::WebElement element = plugin()->container()->element();
     element.setAttribute("placeholderLoaded", "true");
 
     scoped_ptr<content::V8ValueConverter> converter(
@@ -430,7 +327,6 @@ bool LoadablePluginPlaceholder::LoadingBlocked() const {
          is_blocked_for_prerendering_;
 }
 
-#if defined(ENABLE_PLUGINS)
 void LoadablePluginPlaceholder::RecheckSizeAndMaybeUnthrottle() {
   DCHECK(
       content::RenderThread::Get()->GetTaskRunner()->BelongsToCurrentThread());
@@ -448,6 +344,5 @@ void LoadablePluginPlaceholder::RecheckSizeAndMaybeUnthrottle() {
 
   in_size_recheck_ = false;
 }
-#endif  // defined(ENABLE_PLUGINS)
 
 }  // namespace plugins
diff --git a/components/plugins/renderer/loadable_plugin_placeholder.h b/components/plugins/renderer/loadable_plugin_placeholder.h
index 0111dff..13b903d 100644
--- a/components/plugins/renderer/loadable_plugin_placeholder.h
+++ b/components/plugins/renderer/loadable_plugin_placeholder.h
@@ -10,11 +10,12 @@
 #include "components/plugins/renderer/plugin_placeholder.h"
 #include "content/public/common/webplugininfo.h"
 #include "content/public/renderer/plugin_instance_throttler.h"
+#include "content/public/renderer/render_thread.h"
 
 namespace plugins {
 // Placeholders can be used if a plugin is missing or not available
 // (blocked or disabled).
-class LoadablePluginPlaceholder : public PluginPlaceholder {
+class LoadablePluginPlaceholder : public PluginPlaceholderBase {
  public:
   void set_blocked_for_background_tab(bool blocked_for_background_tab) {
     is_blocked_for_background_tab_ = blocked_for_background_tab;
@@ -24,7 +25,6 @@ class LoadablePluginPlaceholder : public PluginPlaceholder {
     is_blocked_for_prerendering_ = blocked_for_prerendering;
   }
 
-#if defined(ENABLE_PLUGINS)
   bool power_saver_enabled() const { return power_saver_enabled_; }
 
   void set_power_saver_enabled(bool power_saver_enabled) {
@@ -36,23 +36,19 @@ class LoadablePluginPlaceholder : public PluginPlaceholder {
 
   // When we load the plugin, use this already-created plugin, not a new one.
   void SetPremadePlugin(content::PluginInstanceThrottler* throttler);
-#endif
 
-  void set_allow_loading(bool allow_loading) { allow_loading_ = allow_loading; }
+  void DisallowLoading() { allow_loading_ = false; }
 
  protected:
   LoadablePluginPlaceholder(content::RenderFrame* render_frame,
                             blink::WebLocalFrame* frame,
                             const blink::WebPluginParams& params,
-                            const std::string& html_data,
-                            GURL placeholderDataUrl);
+                            const std::string& html_data);
 
   ~LoadablePluginPlaceholder() override;
 
-#if defined(ENABLE_PLUGINS)
   void MarkPluginEssential(
       content::PluginInstanceThrottler::PowerSaverUnthrottleMethod method);
-#endif
 
   void OnLoadBlockedPlugins(const std::string& identifier);
   void OnSetIsPrerendering(bool is_prerendering);
@@ -68,42 +64,27 @@ class LoadablePluginPlaceholder : public PluginPlaceholder {
   // a placeholder again).
   void ReplacePlugin(blink::WebPlugin* new_plugin);
 
-  // Hide this placeholder.
-  void HidePlugin();
-
   // Load the blocked plugin.
   void LoadPlugin();
 
-  // WebViewPlugin::Delegate (via PluginPlaceholder) method
-  void BindWebFrame(blink::WebFrame* frame) override;
-
-  // gin::Wrappable method:
-  gin::ObjectTemplateBuilder GetObjectTemplateBuilder(
-      v8::Isolate* isolate) override;
+  // Javascript callbacks:
+  void LoadCallback();
+  void DidFinishLoadingCallback();
 
  private:
   // WebViewPlugin::Delegate methods:
   void PluginDestroyed() override;
   v8::Local<v8::Object> GetV8ScriptableObject(
       v8::Isolate* isolate) const override;
-#if defined(ENABLE_PLUGINS)
   void OnUnobscuredSizeUpdate(const gfx::Size& unobscured_size) override;
-#endif
 
   // RenderFrameObserver methods:
   void WasShown() override;
 
-  // Javascript callbacks:
-  void LoadCallback();
-  void HideCallback();
-  void DidFinishLoadingCallback();
-
   void UpdateMessage();
 
   bool LoadingBlocked() const;
-#if defined(ENABLE_PLUGINS)
   void RecheckSizeAndMaybeUnthrottle();
-#endif
 
   // Plugin creation is embedder-specific.
   virtual blink::WebPlugin* CreatePlugin() = 0;
@@ -132,7 +113,6 @@ class LoadablePluginPlaceholder : public PluginPlaceholder {
 
   bool allow_loading_;
 
-  bool hidden_;
   bool finished_loading_;
   std::string identifier_;
 
diff --git a/components/plugins/renderer/mobile_youtube_plugin.cc b/components/plugins/renderer/mobile_youtube_plugin.cc
index 6db102a..9745a0a 100644
--- a/components/plugins/renderer/mobile_youtube_plugin.cc
+++ b/components/plugins/renderer/mobile_youtube_plugin.cc
@@ -11,10 +11,8 @@
 #include "base/values.h"
 #include "content/public/common/content_constants.h"
 #include "content/public/renderer/render_frame.h"
-#include "gin/handle.h"
 #include "gin/object_template_builder.h"
 #include "third_party/WebKit/public/web/WebFrame.h"
-#include "third_party/WebKit/public/web/WebKit.h"
 #include "ui/base/webui/jstemplate_builder.h"
 
 using blink::WebFrame;
@@ -73,16 +71,17 @@ bool IsValidYouTubeVideo(const std::string& path) {
 
 namespace plugins {
 
+gin::WrapperInfo MobileYouTubePlugin::kWrapperInfo = {gin::kEmbedderNativeGin};
+
 MobileYouTubePlugin::MobileYouTubePlugin(content::RenderFrame* render_frame,
                                          blink::WebLocalFrame* frame,
                                          const blink::WebPluginParams& params,
-                                         base::StringPiece& template_html,
-                                         GURL placeholderDataUrl)
-    : PluginPlaceholder(render_frame,
-                        frame,
-                        params,
-                        HtmlData(params, template_html),
-                        placeholderDataUrl) {}
+                                         base::StringPiece& template_html)
+    : PluginPlaceholderBase(render_frame,
+                            frame,
+                            params,
+                            HtmlData(params, template_html)) {
+}
 
 MobileYouTubePlugin::~MobileYouTubePlugin() {}
 
@@ -108,22 +107,15 @@ void MobileYouTubePlugin::OpenYoutubeUrlCallback() {
       GetFrame(), request, blink::WebNavigationPolicyNewForegroundTab);
 }
 
-void MobileYouTubePlugin::BindWebFrame(WebFrame* frame) {
-  v8::Isolate* isolate = blink::mainThreadIsolate();
-  v8::HandleScope handle_scope(isolate);
-  v8::Local<v8::Context> context = frame->mainWorldScriptContext();
-  DCHECK(!context.IsEmpty());
-
-  v8::Context::Scope context_scope(context);
-  v8::Local<v8::Object> global = context->Global();
-  global->Set(gin::StringToV8(isolate, "plugin"),
-              gin::CreateHandle(isolate, this).ToV8());
+v8::Local<v8::Value> MobileYouTubePlugin::GetV8Handle(v8::Isolate* isolate) {
+  return gin::CreateHandle(isolate, this).ToV8();
 }
 
 gin::ObjectTemplateBuilder MobileYouTubePlugin::GetObjectTemplateBuilder(
     v8::Isolate* isolate) {
-  return PluginPlaceholder::GetObjectTemplateBuilder(isolate)
-    .SetMethod("openYoutubeURL", &MobileYouTubePlugin::OpenYoutubeUrlCallback);
+  return gin::Wrappable<MobileYouTubePlugin>::GetObjectTemplateBuilder(isolate)
+      .SetMethod("openYoutubeURL",
+                 &MobileYouTubePlugin::OpenYoutubeUrlCallback);
 }
 
 }  // namespace plugins
diff --git a/components/plugins/renderer/mobile_youtube_plugin.h b/components/plugins/renderer/mobile_youtube_plugin.h
index 99a6213..9d46700 100644
--- a/components/plugins/renderer/mobile_youtube_plugin.h
+++ b/components/plugins/renderer/mobile_youtube_plugin.h
@@ -14,13 +14,15 @@ namespace plugins {
 // of http://www.youtube.com/v/VIDEO_ID. This placeholder replaces the url with
 // a simple html page and clicking the play image redirects the user to the
 // mobile youtube app.
-class MobileYouTubePlugin : public PluginPlaceholder {
+class MobileYouTubePlugin final : public PluginPlaceholderBase,
+                                  public gin::Wrappable<MobileYouTubePlugin> {
  public:
+  static gin::WrapperInfo kWrapperInfo;
+
   MobileYouTubePlugin(content::RenderFrame* render_frame,
                       blink::WebLocalFrame* frame,
                       const blink::WebPluginParams& params,
-                      base::StringPiece& template_html,
-                      GURL placeholderDataUrl);
+                      base::StringPiece& template_html);
 
   // Whether this is a youtube url.
   static bool IsYouTubeURL(const GURL& url, const std::string& mime_type);
@@ -31,12 +33,12 @@ class MobileYouTubePlugin : public PluginPlaceholder {
   // Opens a youtube app in the current tab.
   void OpenYoutubeUrlCallback();
 
-  // WebViewPlugin::Delegate (via PluginPlaceholder) method
-  void BindWebFrame(blink::WebFrame* frame) override;
+  // WebViewPlugin::Delegate methods:
+  v8::Local<v8::Value> GetV8Handle(v8::Isolate* isolate) override;
 
   // gin::Wrappable (via PluginPlaceholder) method
   gin::ObjectTemplateBuilder GetObjectTemplateBuilder(
-      v8::Isolate* isolate) override;
+      v8::Isolate* isolate) final;
 
   DISALLOW_COPY_AND_ASSIGN(MobileYouTubePlugin);
 };
diff --git a/components/plugins/renderer/plugin_placeholder.cc b/components/plugins/renderer/plugin_placeholder.cc
index 180e913..98fc8cb 100644
--- a/components/plugins/renderer/plugin_placeholder.cc
+++ b/components/plugins/renderer/plugin_placeholder.cc
@@ -4,18 +4,26 @@
 
 #include "components/plugins/renderer/plugin_placeholder.h"
 
+#include "base/strings/string_util.h"
 #include "content/public/common/web_preferences.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/WebElement.h"
+#include "third_party/WebKit/public/web/WebPluginContainer.h"
+#include "third_party/re2/re2/re2.h"
 
 namespace plugins {
 
-gin::WrapperInfo PluginPlaceholder::kWrapperInfo = {gin::kEmbedderNativeGin};
+// The placeholder is loaded in normal web renderer processes, so it should not
+// have a chrome:// scheme that might let it be confused with a WebUI page.
+const char kPluginPlaceholderDataURL[] = "data:text/html,pluginplaceholderdata";
 
-PluginPlaceholder::PluginPlaceholder(content::RenderFrame* render_frame,
-                                     blink::WebLocalFrame* frame,
-                                     const blink::WebPluginParams& params,
-                                     const std::string& html_data,
-                                     GURL placeholderDataUrl)
+PluginPlaceholderBase::PluginPlaceholderBase(
+    content::RenderFrame* render_frame,
+    blink::WebLocalFrame* frame,
+    const blink::WebPluginParams& params,
+    const std::string& html_data)
     : content::RenderFrameObserver(render_frame),
       frame_(frame),
       plugin_params_(params),
@@ -24,36 +32,116 @@ PluginPlaceholder::PluginPlaceholder(content::RenderFrame* render_frame,
                                         ? render_frame->GetWebkitPreferences()
                                         : content::WebPreferences(),
                                     html_data,
-                                    placeholderDataUrl)) {
-  DCHECK(placeholderDataUrl.is_valid())
-      << "Blink requires the placeholder to have a valid URL.";
+                                    GURL(kPluginPlaceholderDataURL))),
+      hidden_(false) {
 }
 
-PluginPlaceholder::~PluginPlaceholder() {}
+PluginPlaceholderBase::~PluginPlaceholderBase() {
+}
 
-const blink::WebPluginParams& PluginPlaceholder::GetPluginParams() const {
+const blink::WebPluginParams& PluginPlaceholderBase::GetPluginParams() const {
   return plugin_params_;
 }
 
-void PluginPlaceholder::ShowContextMenu(const blink::WebMouseEvent& event) {
+void PluginPlaceholderBase::ShowContextMenu(const blink::WebMouseEvent& event) {
   // Does nothing by default. Will be overridden if a specific browser wants
   // a context menu.
   return;
 }
 
-void PluginPlaceholder::PluginDestroyed() {
+void PluginPlaceholderBase::PluginDestroyed() {
   plugin_ = NULL;
 }
 
-v8::Local<v8::Object> PluginPlaceholder::GetV8ScriptableObject(
+v8::Local<v8::Object> PluginPlaceholderBase::GetV8ScriptableObject(
     v8::Isolate* isolate) const {
   return v8::Local<v8::Object>();
 }
 
-void PluginPlaceholder::OnDestruct() {
+void PluginPlaceholderBase::HidePlugin() {
+  hidden_ = true;
+  if (!plugin())
+    return;
+  blink::WebPluginContainer* container = plugin()->container();
+  blink::WebElement element = container->element();
+  element.setAttribute("style", "display: none;");
+  // If we have a width and height, search for a parent (often <div>) with the
+  // same dimensions. If we find such a parent, hide that as well.
+  // This makes much more uncovered page content usable (including clickable)
+  // as opposed to merely visible.
+  // TODO(cevans) -- it's a foul heuristic but we're going to tolerate it for
+  // now for these reasons:
+  // 1) Makes the user experience better.
+  // 2) Foulness is encapsulated within this single function.
+  // 3) Confidence in no fasle positives.
+  // 4) Seems to have a good / low false negative rate at this time.
+  if (element.hasAttribute("width") && element.hasAttribute("height")) {
+    std::string width_str("width:[\\s]*");
+    width_str += element.getAttribute("width").utf8().data();
+    if (EndsWith(width_str, "px", false)) {
+      width_str = width_str.substr(0, width_str.length() - 2);
+    }
+    base::TrimWhitespace(width_str, base::TRIM_TRAILING, &width_str);
+    width_str += "[\\s]*px";
+    std::string height_str("height:[\\s]*");
+    height_str += element.getAttribute("height").utf8().data();
+    if (EndsWith(height_str, "px", false)) {
+      height_str = height_str.substr(0, height_str.length() - 2);
+    }
+    base::TrimWhitespace(height_str, base::TRIM_TRAILING, &height_str);
+    height_str += "[\\s]*px";
+    blink::WebNode parent = element;
+    while (!parent.parentNode().isNull()) {
+      parent = parent.parentNode();
+      if (!parent.isElementNode())
+        continue;
+      element = parent.toConst<blink::WebElement>();
+      if (element.hasAttribute("style")) {
+        std::string style_str = element.getAttribute("style").utf8();
+        if (RE2::PartialMatch(style_str, width_str) &&
+            RE2::PartialMatch(style_str, height_str))
+          element.setAttribute("style", "display: none;");
+      }
+    }
+  }
+}
+
+void PluginPlaceholderBase::HideCallback() {
+  content::RenderThread::Get()->RecordAction(
+      base::UserMetricsAction("Plugin_Hide_Click"));
+  HidePlugin();
+}
+
+void PluginPlaceholderBase::OnDestruct() {
   frame_ = NULL;
 }
 
-blink::WebLocalFrame* PluginPlaceholder::GetFrame() { return frame_; }
+blink::WebLocalFrame* PluginPlaceholderBase::GetFrame() {
+  return frame_;
+}
+
+// static
+gin::WrapperInfo PluginPlaceholder::kWrapperInfo = {gin::kEmbedderNativeGin};
+
+PluginPlaceholder::PluginPlaceholder(content::RenderFrame* render_frame,
+                                     blink::WebLocalFrame* frame,
+                                     const blink::WebPluginParams& params,
+                                     const std::string& html_data)
+    : PluginPlaceholderBase(render_frame, frame, params, html_data) {
+}
+
+PluginPlaceholder::~PluginPlaceholder() {
+}
+
+v8::Local<v8::Value> PluginPlaceholder::GetV8Handle(v8::Isolate* isolate) {
+  return gin::CreateHandle(isolate, this).ToV8();
+}
+
+gin::ObjectTemplateBuilder PluginPlaceholder::GetObjectTemplateBuilder(
+    v8::Isolate* isolate) {
+  return gin::Wrappable<PluginPlaceholder>::GetObjectTemplateBuilder(isolate)
+      .SetMethod<void (plugins::PluginPlaceholder::*)()>(
+          "hide", &PluginPlaceholder::HideCallback);
+}
 
 }  // namespace plugins
diff --git a/components/plugins/renderer/plugin_placeholder.h b/components/plugins/renderer/plugin_placeholder.h
index 5d9caa1..63a1d08 100644
--- a/components/plugins/renderer/plugin_placeholder.h
+++ b/components/plugins/renderer/plugin_placeholder.h
@@ -8,30 +8,29 @@
 #include "base/memory/weak_ptr.h"
 #include "components/plugins/renderer/webview_plugin.h"
 #include "content/public/renderer/render_frame_observer.h"
+#include "gin/handle.h"
 #include "gin/wrappable.h"
+#include "third_party/WebKit/public/web/WebKit.h"
 #include "third_party/WebKit/public/web/WebPluginParams.h"
 
 namespace plugins {
 
-class PluginPlaceholder : public content::RenderFrameObserver,
-                          public WebViewPlugin::Delegate,
-                          public gin::Wrappable<PluginPlaceholder> {
+// This abstract class is the base class of all plugin placeholders.
+class PluginPlaceholderBase : public content::RenderFrameObserver,
+                              public WebViewPlugin::Delegate {
  public:
-  static gin::WrapperInfo kWrapperInfo;
-
-  WebViewPlugin* plugin() { return plugin_; }
-
- protected:
   // |render_frame| and |frame| are weak pointers. If either one is going away,
   // our |plugin_| will be destroyed as well and will notify us.
-  PluginPlaceholder(content::RenderFrame* render_frame,
-                    blink::WebLocalFrame* frame,
-                    const blink::WebPluginParams& params,
-                    const std::string& html_data,
-                    GURL placeholderDataUrl);
+  PluginPlaceholderBase(content::RenderFrame* render_frame,
+                        blink::WebLocalFrame* frame,
+                        const blink::WebPluginParams& params,
+                        const std::string& html_data);
 
-  ~PluginPlaceholder() override;
+  ~PluginPlaceholderBase() override;
+
+  WebViewPlugin* plugin() { return plugin_; }
 
+ protected:
   blink::WebLocalFrame* GetFrame();
   const blink::WebPluginParams& GetPluginParams() const;
 
@@ -41,6 +40,14 @@ class PluginPlaceholder : public content::RenderFrameObserver,
   v8::Local<v8::Object> GetV8ScriptableObject(
       v8::Isolate* isolate) const override;
 
+ protected:
+  // Hide this placeholder.
+  void HidePlugin();
+  bool hidden() { return hidden_; }
+
+  // JavaScript callbacks:
+  void HideCallback();
+
  private:
   // RenderFrameObserver methods:
   void OnDestruct() override;
@@ -49,7 +56,30 @@ class PluginPlaceholder : public content::RenderFrameObserver,
   blink::WebPluginParams plugin_params_;
   WebViewPlugin* plugin_;
 
-  DISALLOW_COPY_AND_ASSIGN(PluginPlaceholder);
+  bool hidden_;
+
+  DISALLOW_COPY_AND_ASSIGN(PluginPlaceholderBase);
+};
+
+// A basic placeholder that supports only hiding.
+class PluginPlaceholder final : public PluginPlaceholderBase,
+                                public gin::Wrappable<PluginPlaceholder> {
+ public:
+  static gin::WrapperInfo kWrapperInfo;
+
+  PluginPlaceholder(content::RenderFrame* render_frame,
+                    blink::WebLocalFrame* frame,
+                    const blink::WebPluginParams& params,
+                    const std::string& html_data);
+  ~PluginPlaceholder() override;
+
+ private:
+  // WebViewPlugin::Delegate methods:
+  v8::Local<v8::Value> GetV8Handle(v8::Isolate* isolate) final;
+
+  // gin::Wrappable method:
+  gin::ObjectTemplateBuilder GetObjectTemplateBuilder(
+      v8::Isolate* isolate) override;
 };
 
 }  // namespace plugins
diff --git a/components/plugins/renderer/webview_plugin.cc b/components/plugins/renderer/webview_plugin.cc
index 43cd43e..0779566 100644
--- a/components/plugins/renderer/webview_plugin.cc
+++ b/components/plugins/renderer/webview_plugin.cc
@@ -9,6 +9,7 @@
 #include "base/numerics/safe_conversions.h"
 #include "content/public/common/web_preferences.h"
 #include "content/public/renderer/render_view.h"
+#include "gin/converter.h"
 #include "skia/ext/platform_canvas.h"
 #include "third_party/WebKit/public/platform/WebSize.h"
 #include "third_party/WebKit/public/platform/WebURL.h"
@@ -61,6 +62,7 @@ WebViewPlugin* WebViewPlugin::Create(WebViewPlugin::Delegate* delegate,
                                      const WebPreferences& preferences,
                                      const std::string& html_data,
                                      const GURL& url) {
+  DCHECK(url.is_valid()) << "Blink requires the WebView to have a valid URL.";
   WebViewPlugin* plugin = new WebViewPlugin(delegate, preferences);
   plugin->web_view()->mainFrame()->loadHTMLString(html_data, url);
   return plugin;
@@ -264,8 +266,19 @@ void WebViewPlugin::scheduleAnimation() {
 }
 
 void WebViewPlugin::didClearWindowObject(WebLocalFrame* frame) {
-  if (delegate_)
-    delegate_->BindWebFrame(frame);
+  if (!delegate_)
+    return;
+
+  v8::Isolate* isolate = blink::mainThreadIsolate();
+  v8::HandleScope handle_scope(isolate);
+  v8::Local<v8::Context> context = frame->mainWorldScriptContext();
+  DCHECK(!context.IsEmpty());
+
+  v8::Context::Scope context_scope(context);
+  v8::Local<v8::Object> global = context->Global();
+
+  global->Set(gin::StringToV8(isolate, "plugin"),
+              delegate_->GetV8Handle(isolate));
 }
 
 void WebViewPlugin::didReceiveResponse(WebLocalFrame* frame,
diff --git a/components/plugins/renderer/webview_plugin.h b/components/plugins/renderer/webview_plugin.h
index 3286fae..fdb9777 100644
--- a/components/plugins/renderer/webview_plugin.h
+++ b/components/plugins/renderer/webview_plugin.h
@@ -13,6 +13,7 @@
 #include "third_party/WebKit/public/platform/WebString.h"
 #include "third_party/WebKit/public/platform/WebURLResponse.h"
 #include "third_party/WebKit/public/web/WebFrameClient.h"
+#include "third_party/WebKit/public/web/WebKit.h"
 #include "third_party/WebKit/public/web/WebPlugin.h"
 #include "third_party/WebKit/public/web/WebViewClient.h"
 
@@ -42,10 +43,8 @@ class WebViewPlugin : public blink::WebPlugin,
  public:
   class Delegate {
    public:
-    // Bind |frame| to a Javascript object, enabling the delegate to receive
-    // callback methods from Javascript inside the WebFrame.
-    // This method is called from WebFrameClient::didClearWindowObject.
-    virtual void BindWebFrame(blink::WebFrame* frame) = 0;
+    // Called to get the V8 handle used to bind the lifetime to the frame.
+    virtual v8::Local<v8::Value> GetV8Handle(v8::Isolate*) = 0;
 
     // Called upon a context menu event.
     virtual void ShowContextMenu(const blink::WebMouseEvent&) = 0;
diff --git a/content/content_shell.gypi b/content/content_shell.gypi
index 2f30de3..5e65727 100644
--- a/content/content_shell.gypi
+++ b/content/content_shell.gypi
@@ -226,8 +226,6 @@
         'shell/renderer/layout_test/leak_detector.h',
         'shell/renderer/layout_test/test_media_stream_renderer_factory.cc',
         'shell/renderer/layout_test/test_media_stream_renderer_factory.h',
-        'shell/renderer/layout_test/test_plugin_placeholder.cc',
-        'shell/renderer/layout_test/test_plugin_placeholder.h',
         'shell/renderer/layout_test/test_video_frame_provider.cc',
         'shell/renderer/layout_test/test_video_frame_provider.h',
         'shell/renderer/shell_content_renderer_client.cc',
diff --git a/content/shell/BUILD.gn b/content/shell/BUILD.gn
index d505da3..b736942 100644
--- a/content/shell/BUILD.gn
+++ b/content/shell/BUILD.gn
@@ -162,8 +162,6 @@ static_library("content_shell_lib") {
     "renderer/layout_test/leak_detector.h",
     "renderer/layout_test/test_media_stream_renderer_factory.cc",
     "renderer/layout_test/test_media_stream_renderer_factory.h",
-    "renderer/layout_test/test_plugin_placeholder.cc",
-    "renderer/layout_test/test_plugin_placeholder.h",
     "renderer/layout_test/test_video_frame_provider.cc",
     "renderer/layout_test/test_video_frame_provider.h",
     "renderer/shell_content_renderer_client.cc",
diff --git a/content/shell/renderer/layout_test/blink_test_runner.cc b/content/shell/renderer/layout_test/blink_test_runner.cc
index 009f475..ebba115 100644
--- a/content/shell/renderer/layout_test/blink_test_runner.cc
+++ b/content/shell/renderer/layout_test/blink_test_runner.cc
@@ -23,6 +23,7 @@
 #include "base/strings/utf_string_conversions.h"
 #include "base/thread_task_runner_handle.h"
 #include "base/time/time.h"
+#include "components/plugins/renderer/plugin_placeholder.h"
 #include "components/test_runner/app_banner_client.h"
 #include "components/test_runner/gamepad_controller.h"
 #include "components/test_runner/mock_screen_orientation_client.h"
@@ -46,7 +47,6 @@
 #include "content/shell/renderer/layout_test/gc_controller.h"
 #include "content/shell/renderer/layout_test/layout_test_render_process_observer.h"
 #include "content/shell/renderer/layout_test/leak_detector.h"
-#include "content/shell/renderer/layout_test/test_plugin_placeholder.h"
 #include "net/base/filename_util.h"
 #include "net/base/net_errors.h"
 #include "skia/ext/platform_canvas.h"
@@ -688,10 +688,13 @@ void BlinkTestRunner::ResolveBeforeInstallPromptPromise(
 
 blink::WebPlugin* BlinkTestRunner::CreatePluginPlaceholder(
     blink::WebLocalFrame* frame, const blink::WebPluginParams& params) {
-  if (params.mimeType == "application/x-plugin-placeholder-test")
-    return (new TestPluginPlaceholder(render_view()->GetMainRenderFrame(),
-                                      frame, params))->plugin();
-  return 0;
+  if (params.mimeType != "application/x-plugin-placeholder-test")
+    return nullptr;
+
+  plugins::PluginPlaceholder* placeholder =
+      new plugins::PluginPlaceholder(render_view()->GetMainRenderFrame(), frame,
+                                     params, "<div>Test content</div>");
+  return placeholder->plugin();
 }
 
 // RenderViewObserver  --------------------------------------------------------
diff --git a/content/shell/renderer/layout_test/test_plugin_placeholder.cc b/content/shell/renderer/layout_test/test_plugin_placeholder.cc
deleted file mode 100644
index 5b5a071..0000000
--- a/content/shell/renderer/layout_test/test_plugin_placeholder.cc
+++ /dev/null
@@ -1,35 +0,0 @@
-// Copyright 2015 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 "content/shell/renderer/layout_test/test_plugin_placeholder.h"
-
-#include "gin/handle.h"
-#include "third_party/WebKit/public/web/WebKit.h"
-
-namespace content {
-
-TestPluginPlaceholder::TestPluginPlaceholder(
-    RenderFrame* render_frame,
-    blink::WebLocalFrame* frame,
-    const blink::WebPluginParams& params)
-    : PluginPlaceholder(render_frame,
-                        frame,
-                        params,
-                        "<div>Test content</div>",
-                        GURL("http://www.test.com")) {
-}
-
-void TestPluginPlaceholder::BindWebFrame(blink::WebFrame* frame) {
-  v8::Isolate* isolate = blink::mainThreadIsolate();
-  v8::HandleScope handle_scope(isolate);
-  v8::Local<v8::Context> context = frame->mainWorldScriptContext();
-  DCHECK(!context.IsEmpty());
-
-  v8::Context::Scope context_scope(context);
-  v8::Local<v8::Object> global = context->Global();
-  global->Set(gin::StringToV8(isolate, "plugin"),
-              gin::CreateHandle(isolate, this).ToV8());
-}
-
-}  // namespace content
diff --git a/content/shell/renderer/layout_test/test_plugin_placeholder.h b/content/shell/renderer/layout_test/test_plugin_placeholder.h
deleted file mode 100644
index 1424923..0000000
--- a/content/shell/renderer/layout_test/test_plugin_placeholder.h
+++ /dev/null
@@ -1,23 +0,0 @@
-// Copyright 2015 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 CONTENT_SHELL_RENDERER_TEST_RUNNER_TEST_PLUGIN_PLACEHOLDER_H_
-#define CONTENT_SHELL_RENDERER_TEST_RUNNER_TEST_PLUGIN_PLACEHOLDER_H_
-
-#include "components/plugins/renderer/plugin_placeholder.h"
-
-namespace content {
-
-// A subclass of PluginPlaceholder for use in Blink layout tests.
-class TestPluginPlaceholder : public plugins::PluginPlaceholder {
- public:
-  TestPluginPlaceholder(RenderFrame* render_frame,
-                        blink::WebLocalFrame* frame,
-                        const blink::WebPluginParams& params);
-
-  void BindWebFrame(blink::WebFrame* frame) override;
-};
-
-}  // namespace content
-
-#endif  // CONTENT_SHELL_RENDERER_TEST_RUNNER_TEST_PLUGIN_PLACEHOLDER_H_
diff --git a/gin/wrappable.cc b/gin/wrappable.cc
index 27c58df..0fac4e0 100644
--- a/gin/wrappable.cc
+++ b/gin/wrappable.cc
@@ -36,7 +36,7 @@ void WrappableBase::SecondWeakCallback(
 }
 
 v8::Local<v8::Object> WrappableBase::GetWrapperImpl(v8::Isolate* isolate,
-                                                     WrapperInfo* info) {
+                                                    WrapperInfo* info) {
   if (!wrapper_.IsEmpty()) {
     return v8::Local<v8::Object>::New(isolate, wrapper_);
   }
diff --git a/gin/wrappable.h b/gin/wrappable.h
index cd4d30e..f7d82b0 100644
--- a/gin/wrappable.h
+++ b/gin/wrappable.h
@@ -12,15 +12,6 @@
 
 namespace gin {
 
-namespace internal {
-
-GIN_EXPORT void* FromV8Impl(v8::Isolate* isolate,
-                            v8::Local<v8::Value> val,
-                            WrapperInfo* info);
-
-}  // namespace internal
-
-
 // Wrappable is a base class for C++ objects that have corresponding v8 wrapper
 // objects. To retain a Wrappable object on the stack, use a gin::Handle.
 //
@@ -51,8 +42,20 @@ GIN_EXPORT void* FromV8Impl(v8::Isolate* isolate,
 // wrapper for the object. If clients fail to create a wrapper for a wrappable
 // object, the object will leak because we use the weak callback from the
 // wrapper as the signal to delete the wrapped object.
-template<typename T>
-class Wrappable;
+//
+// Wrappable<T> explicitly does not support further subclassing of T.
+// Subclasses of Wrappable<T> should be declared final. Because Wrappable<T>
+// caches the object template using &T::kWrapperInfo as the key, all subclasses
+// would share a single object template. This will lead to hard to debug crashes
+// that look like use-after-free errors.
+
+namespace internal {
+
+GIN_EXPORT void* FromV8Impl(v8::Isolate* isolate,
+                            v8::Local<v8::Value> val,
+                            WrapperInfo* info);
+
+}  // namespace internal
 
 class ObjectTemplateBuilder;
 
@@ -62,6 +65,7 @@ class GIN_EXPORT WrappableBase {
   WrappableBase();
   virtual ~WrappableBase();
 
+  // Overrides of this method should be declared final and not overridden again.
   virtual ObjectTemplateBuilder GetObjectTemplateBuilder(v8::Isolate* isolate);
 
   v8::Local<v8::Object> GetWrapperImpl(v8::Isolate* isolate,
@@ -83,8 +87,6 @@ template<typename T>
 class Wrappable : public WrappableBase {
  public:
   // Retrieve (or create) the v8 wrapper object cooresponding to this object.
-  // To customize the wrapper created for a subclass, override GetWrapperInfo()
-  // instead of overriding this function.
   v8::Local<v8::Object> GetWrapper(v8::Isolate* isolate) {
     return GetWrapperImpl(isolate, &T::kWrapperInfo);
   }
diff --git a/gin/wrappable_unittest.cc b/gin/wrappable_unittest.cc
index 70cb224..07d4fb3 100644
--- a/gin/wrappable_unittest.cc
+++ b/gin/wrappable_unittest.cc
@@ -40,38 +40,16 @@ class MyObject : public BaseClass,
 
  protected:
   MyObject() : value_(0) {}
-  ObjectTemplateBuilder GetObjectTemplateBuilder(v8::Isolate* isolate) override;
+  ObjectTemplateBuilder GetObjectTemplateBuilder(v8::Isolate* isolate) final {
+    return Wrappable<MyObject>::GetObjectTemplateBuilder(isolate)
+        .SetProperty("value", &MyObject::value, &MyObject::set_value);
+  }
   ~MyObject() override {}
 
  private:
   int value_;
 };
 
-class MyObjectSubclass : public MyObject {
- public:
-  static gin::Handle<MyObjectSubclass> Create(v8::Isolate* isolate) {
-    return CreateHandle(isolate, new MyObjectSubclass());
-  }
-
-  void SayHello(const std::string& name) {
-    result = std::string("Hello, ") + name;
-  }
-
-  std::string result;
-
- private:
-  ObjectTemplateBuilder GetObjectTemplateBuilder(
-      v8::Isolate* isolate) override {
-    return MyObject::GetObjectTemplateBuilder(isolate)
-        .SetMethod("sayHello", &MyObjectSubclass::SayHello);
-  }
-
-  MyObjectSubclass() {
-  }
-
-  ~MyObjectSubclass() override {}
-};
-
 class MyCallableObject : public Wrappable<MyCallableObject> {
  public:
   static WrapperInfo kWrapperInfo;
@@ -83,8 +61,7 @@ class MyCallableObject : public Wrappable<MyCallableObject> {
   int result() { return result_; }
 
  private:
-  ObjectTemplateBuilder GetObjectTemplateBuilder(
-      v8::Isolate* isolate) override {
+  ObjectTemplateBuilder GetObjectTemplateBuilder(v8::Isolate* isolate) final {
     return Wrappable<MyCallableObject>::GetObjectTemplateBuilder(isolate)
         .SetCallAsFunctionHandler(&MyCallableObject::Call);
   }
@@ -109,20 +86,9 @@ class MyObject2 : public Wrappable<MyObject2> {
   static WrapperInfo kWrapperInfo;
 };
 
-class MyObjectBlink : public Wrappable<MyObjectBlink> {
- public:
-  static WrapperInfo kWrapperInfo;
-};
-
 WrapperInfo MyObject::kWrapperInfo = { kEmbedderNativeGin };
-ObjectTemplateBuilder MyObject::GetObjectTemplateBuilder(v8::Isolate* isolate) {
-  return Wrappable<MyObject>::GetObjectTemplateBuilder(isolate)
-      .SetProperty("value", &MyObject::value, &MyObject::set_value);
-}
-
 WrapperInfo MyCallableObject::kWrapperInfo = { kEmbedderNativeGin };
 WrapperInfo MyObject2::kWrapperInfo = { kEmbedderNativeGin };
-WrapperInfo MyObjectBlink::kWrapperInfo = { kEmbedderNativeGin };
 
 typedef V8Test WrappableTest;
 
@@ -155,12 +121,6 @@ TEST_F(WrappableTest, UnwrapFailures) {
   EXPECT_FALSE(ConvertFromV8(isolate, thing, &unwrapped));
   EXPECT_FALSE(unwrapped);
 
-  // An object that's wrapping a C++ object from Blink.
-  thing.Clear();
-  thing = ConvertToV8(isolate, new MyObjectBlink());
-  EXPECT_FALSE(ConvertFromV8(isolate, thing, &unwrapped));
-  EXPECT_FALSE(unwrapped);
-
   // An object that's wrapping a C++ object of the wrong type.
   thing.Clear();
   thing = ConvertToV8(isolate, new MyObject2());
@@ -200,28 +160,6 @@ TEST_F(WrappableTest, GetAndSetProperty) {
   EXPECT_EQ(191, obj->value());
 }
 
-TEST_F(WrappableTest, WrappableSubclass) {
-  v8::Isolate* isolate = instance_->isolate();
-  v8::HandleScope handle_scope(isolate);
-
-  gin::Handle<MyObjectSubclass> object(MyObjectSubclass::Create(isolate));
-  v8::Local<v8::String> source = StringToV8(isolate,
-                                             "(function(obj) {"
-                                             "obj.sayHello('Lily');"
-                                             "})");
-  gin::TryCatch try_catch(isolate);
-  v8::Local<v8::Script> script = v8::Script::Compile(source);
-  v8::Local<v8::Value> val = script->Run();
-  v8::Local<v8::Function> func;
-  EXPECT_TRUE(ConvertFromV8(isolate, val, &func));
-  v8::Local<v8::Value> argv[] = {
-    ConvertToV8(isolate, object.get())
-  };
-  func->Call(v8::Undefined(isolate), 1, argv);
-  EXPECT_FALSE(try_catch.HasCaught());
-  EXPECT_EQ("Hello, Lily", object->result);
-}
-
 TEST_F(WrappableTest, CallAsFunction) {
   v8::Isolate* isolate = instance_->isolate();
   v8::HandleScope handle_scope(isolate);