Add instrumentation to help tracking issue 638400.

content/renderer/render_frame_impl.h

 // 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.
 
 #ifndef CONTENT_RENDERER_RENDER_FRAME_IMPL_H_
 #define CONTENT_RENDERER_RENDER_FRAME_IMPL_H_
 
 #include <stddef.h>
 #include <stdint.h>
 
@@ skipping 1249 matching lines @@
   PepperPluginSet active_pepper_instances_;
 
   // Whether or not the focus is on a PPAPI plugin
   PepperPluginInstanceImpl* focused_pepper_plugin_;
 
   // The plugin instance that received the last mouse event. It is set to NULL
   // if the last mouse event went to elements other than Pepper plugins.
   // |pepper_last_mouse_event_target_| is not owned by this class. We depend on
   // the RenderFrameImpl to NULL it out when it destructs.
   PepperPluginInstanceImpl* pepper_last_mouse_event_target_;
+
+  // TODO(lfg): Temporary to help debug issue https://crbug.com/638400.
+  bool is_plugin_initializing_;
 #endif
 
   mojo::Binding<mojom::Frame> frame_binding_;
   mojom::FrameHostPtr frame_host_;
 
   // Indicates whether |didAccessInitialDocument| was called.
   bool has_accessed_initial_document_;
 
   base::WeakPtrFactory<RenderFrameImpl> weak_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(RenderFrameImpl);
 };
 
 }  // namespace content
 
 #endif  // CONTENT_RENDERER_RENDER_FRAME_IMPL_H_