Plugin Power Saver: Fix a dangling WebViewPlugin.

components/plugins/renderer/loadable_plugin_placeholder.cc

 // 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 "components/plugins/renderer/loadable_plugin_placeholder.h"
 
 #include <memory>
 
 #include "base/bind.h"
 #include "base/bind_helpers.h"
@@ skipping 86 matching lines @@
   if (!new_plugin)
     return;
   blink::WebPluginContainer* container = plugin()->container();
   // This can occur if the container has been destroyed.
   if (!container) {
     new_plugin->destroy();
     return;
   }
 
   container->setPlugin(new_plugin);
-  // Save the element in case the plugin is removed from the page during
-  // initialization.
-  blink::WebElement element = container->element();
   bool plugin_needs_initialization =
       !premade_throttler_ || new_plugin != premade_throttler_->GetWebPlugin();
   if (plugin_needs_initialization && !new_plugin->initialize(container)) {
     if (new_plugin->container()) {
       // Since the we couldn't initialize the new plugin, but the container
       // still exists, restore the placeholder and destroy the new plugin.
       container->setPlugin(plugin());
       new_plugin->destroy();
+    } else {
+      // The container has been destroyed, along with the new plugin. Destroy
+      // our placeholder plugin also.
+      plugin()->destroy();
     }
     return;
   }
 
-  // The plugin has been removed from the page. Destroy the old plugin. We
-  // will be destroyed as soon as V8 garbage collects us.
-  if (!element.pluginContainer()) {
-    plugin()->destroy();
-    return;
-  }
-
   // During initialization, the new plugin might have replaced itself in turn
   // with another plugin. Make sure not to use the passed in |new_plugin| after
   // this point.
   new_plugin = container->plugin();
 
   plugin()->RestoreTitleText();
   container->invalidate();
   container->reportGeometry();
   plugin()->ReplayReceivedData(new_plugin);
   plugin()->destroy();
@@ skipping 226 matching lines @@
   return identifier_;
 }
 
 bool LoadablePluginPlaceholder::LoadingBlocked() const {
   DCHECK(allow_loading_);
   return is_blocked_for_tinyness_ || is_blocked_for_background_tab_ ||
          is_blocked_for_power_saver_poster_ || is_blocked_for_prerendering_;
 }
 
 }  // namespace plugins