Introduce RenderFrame::IsMainFrame and clean up a few things.

content/public/renderer/render_frame.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_PUBLIC_RENDERER_RENDER_FRAME_H_
 #define CONTENT_PUBLIC_RENDERER_RENDER_FRAME_H_
 
 #include "base/callback_forward.h"
 #include "base/memory/scoped_ptr.h"
 #include "base/strings/string16.h"
@@ skipping 97 matching lines @@
       scoped_ptr<PluginInstanceThrottler> throttler) = 0;
 
   // The client should handle the navigation externally.
   virtual void LoadURLExternally(blink::WebLocalFrame* frame,
                                  const blink::WebURLRequest& request,
                                  blink::WebNavigationPolicy policy) = 0;
 
   // Execute a string of JavaScript in this frame's context.
   virtual void ExecuteJavaScript(const base::string16& javascript) = 0;
 
+  // Returns true if this is the main frame
+  // (That's the frame at the top of the frame tree).

[Charlie Reis, 2015/09/26 00:08:04]

nit: No need for the clarification, I think.  At most, "the main (top-level)
frame" would be sufficient.

[dglazkov, 2015/09/28 04:03:35]

Done.

+  virtual bool IsMainFrame() = 0;
+
   // Return true if this frame is hidden.
   virtual bool IsHidden() = 0;
 
   // Returns the ServiceRegistry for this frame.
   virtual ServiceRegistry* GetServiceRegistry() = 0;
 
 #if defined(ENABLE_PLUGINS)
   // Registers a plugin that has been marked peripheral. If the origin
   // whitelist is later updated and includes |content_origin|, then
   // |unthrottle_callback| will be called.
@@ skipping 32 matching lines @@
 
  private:
   // This interface should only be implemented inside content.
   friend class RenderFrameImpl;
   RenderFrame() {}
 };
 
 }  // namespace content
 
 #endif  // CONTENT_PUBLIC_RENDERER_RENDER_FRAME_H_