PlzNavigate: properly execute BeforeUnload on renderer initiated navigations

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 880 matching lines @@
 
   // Creates a factory object used for creating audio and video renderers.
   std::unique_ptr<MediaStreamRendererFactory> CreateRendererFactory();
 
   // Does preparation for the navigation to |url|.
   void PrepareRenderViewForNavigation(
       const GURL& url,
       const RequestNavigationParams& request_params);
 
   // PlzNavigate
-  // Sends a FrameHostMsg_BeginNavigation to the browser based on the contents
-  // of the WebURLRequest.
+  // Called when a navigation should be sent to the browser via a
+  // FrameHostMsg_BeginNavigation IPC (based on the contents of |request|).
+  // Returns true if the navigation was actually sent to the browser, false
+  // otherwise.
   // |should_replace_current_entry| indicates that the current history entry
   // will be replaced when the navigation commits.  |is_client_redirect|
   // indicates that the navigation originated as a client redirect.
   // Note: those two concepts are separate. For example, a location.assign is a
   // client redirect but it only replaces the current entry if called before
   // load stop. location.replace on the other hand is a client redirect and
   // always replaces the current entry.
-  void BeginNavigation(blink::WebURLRequest* request,
+  bool BeginNavigation(blink::WebURLRequest* request,
                        bool should_replace_current_entry,
                        bool is_client_redirect);
 
   // Loads a data url.
   void LoadDataURL(const CommonNavigationParams& params,
                    const RequestNavigationParams& request_params,
                    blink::WebLocalFrame* frame,
                    blink::WebFrameLoadType load_type,
                    blink::WebHistoryItem item_for_history_navigation,
                    blink::WebHistoryLoadType history_load_type,
@@ skipping 306 matching lines @@
   FrameBlameContext* blame_context_;  // Not owned.
 
   base::WeakPtrFactory<RenderFrameImpl> weak_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(RenderFrameImpl);
 };
 
 }  // namespace content
 
 #endif  // CONTENT_RENDERER_RENDER_FRAME_IMPL_H_