Fix RenderWidgetHostViewGuest leak.

content/browser/renderer_host/render_widget_host_view_mac.mm

 // Copyright (c) 2012 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 "content/browser/renderer_host/render_widget_host_view_mac.h"
 
 #import <objc/runtime.h>
 #include <OpenGL/gl.h>
 #include <QuartzCore/QuartzCore.h>
 
@@ skipping 552 matching lines @@
   cocoa_view_ = nil;
 
   UnlockMouse();
 
   // Ensure that the browser compositor is destroyed in a safe order.
   ShutdownBrowserCompositor();
 
   // We are owned by RenderWidgetHostViewCocoa, so if we go away before the
   // RenderWidgetHost does we need to tell it not to hold a stale pointer to
   // us.
-  if (render_widget_host_)
-    render_widget_host_->SetView(NULL);
+  if (render_widget_host_) {
+    if (render_widget_host_->GetView() == this)
+      render_widget_host_->SetView(NULL);

[lazyboy, 2014/10/10 01:22:58]

It might be consistent to call
render_widget_host_->ViewDestroyed() instead.

That function has additional
RWH::RejectMouseLockOrUnlockIfNecessary() call though, so
not sure about the side effect.

+  }
 }
 
 void RenderWidgetHostViewMac::SetDelegate(
     NSObject<RenderWidgetHostViewMacDelegate>* delegate) {
   [cocoa_view_ setResponderDelegate:delegate];
 }
 
 void RenderWidgetHostViewMac::SetAllowPauseForResizeOrRepaint(bool allow) {
   allow_pause_for_resize_or_repaint_ = allow;
 }
@@ skipping 2732 matching lines @@
 
 // "-webkit-app-region: drag | no-drag" is implemented on Mac by excluding
 // regions that are not draggable. (See ControlRegionView in
 // native_app_window_cocoa.mm). This requires the render host view to be
 // draggable by default.
 - (BOOL)mouseDownCanMoveWindow {
   return YES;
 }
 
 @end