PlzNavigate: properly execute BeforeUnload on renderer initiated navigations

content/renderer/render_frame_impl.h

Index: content/renderer/render_frame_impl.h
diff --git a/content/renderer/render_frame_impl.h b/content/renderer/render_frame_impl.h
index a5db1f9e5af3defa814da4607ad07fa480a3f753..942a5b09b9172a7e3c14e27ff4bbd9533100096e 100644
--- a/content/renderer/render_frame_impl.h
+++ b/content/renderer/render_frame_impl.h
@@ -898,8 +898,10 @@ class CONTENT_EXPORT RenderFrameImpl
       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.
@@ -907,7 +909,7 @@ class CONTENT_EXPORT RenderFrameImpl
   // 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);