Fix PPLT metric for the new TabContents based prerendering

chrome/browser/prerender/prerender_render_view_host_observer.cc

 // Copyright (c) 2011 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 "chrome/browser/prerender/prerender_render_view_host_observer.h"
 
 #include "chrome/browser/prerender/prerender_contents.h"
 #include "chrome/common/icon_messages.h"
 #include "chrome/common/render_messages.h"
 #include "content/common/view_messages.h"
@@ skipping 16 matching lines @@
 
 bool PrerenderRenderViewHostObserver::OnMessageReceived(
     const IPC::Message& message) {
   if (!prerender_contents_)
     return RenderViewHostObserver::OnMessageReceived(message);
 
   bool handled = true;
   IPC_BEGIN_MESSAGE_MAP(PrerenderRenderViewHostObserver, message)
     IPC_MESSAGE_HANDLER(ViewHostMsg_DidStartProvisionalLoadForFrame,
                         OnDidStartProvisionalLoadForFrame)
+    IPC_MESSAGE_UNHANDLED(handled = false)
+  IPC_END_MESSAGE_MAP()
+
+  // If this was a DidStartProvisionalLoadForFrame message, we don't want to
+  // to consume it, so return false;
+  if (handled)
+    return false;
+
+  // The following messages we do want to consume.
+  handled = true;
+  IPC_BEGIN_MESSAGE_MAP(PrerenderRenderViewHostObserver, message)
     IPC_MESSAGE_HANDLER(IconHostMsg_UpdateFaviconURL, OnUpdateFaviconURL)
     IPC_MESSAGE_HANDLER(ViewHostMsg_MaybeCancelPrerenderForHTML5Media,
                         OnMaybeCancelPrerenderForHTML5Media)
     IPC_MESSAGE_HANDLER(ViewHostMsg_JSOutOfMemory, OnJSOutOfMemory)
     IPC_MESSAGE_HANDLER(ViewHostMsg_RunJavaScriptMessage,
                         OnRunJavaScriptMessage)
     IPC_MESSAGE_HANDLER(ViewHostMsg_RenderViewGone, OnRenderViewGone)
     IPC_MESSAGE_HANDLER(ViewHostMsg_CancelPrerenderForPrinting,
                         OnCancelPrerenderForPrinting)
     IPC_MESSAGE_UNHANDLED(handled = false)
@@ skipping 55 matching lines @@
 
 void PrerenderRenderViewHostObserver::OnMaybeCancelPrerenderForHTML5Media() {
   prerender_contents_->Destroy(FINAL_STATUS_HTML5_MEDIA);
 }
 
 void PrerenderRenderViewHostObserver::OnCancelPrerenderForPrinting() {
   prerender_contents_->Destroy(FINAL_STATUS_WINDOW_PRINT);
 }
 
 }