Fix crash when destroying a RenderWidgetHost that holds the pointer

content/browser/renderer_host/render_widget_host_delegate.h

 // 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.
 
 #ifndef CONTENT_BROWSER_RENDERER_HOST_RENDER_WIDGET_HOST_DELEGATE_H_
 #define CONTENT_BROWSER_RENDERER_HOST_RENDER_WIDGET_HOST_DELEGATE_H_
 
 #include <stdint.h>
 
 #include <vector>
@@ skipping 149 matching lines @@
   // Returns the display mode for the view.
   virtual blink::WebDisplayMode GetDisplayMode(
       RenderWidgetHostImpl* render_widget_host) const;
 
   // Notification that the widget has lost capture.
   virtual void LostCapture(RenderWidgetHostImpl* render_widget_host) {}
 
   // Notification that the widget has lost the mouse lock.
   virtual void LostMouseLock(RenderWidgetHostImpl* render_widget_host) {}
 
+  // Returns true if |render_widget_host| holds the mouse lock.
+  virtual bool HasMouseLock(RenderWidgetHostImpl* render_widget_host) = 0;

[Charlie Reis, 2016/07/06 17:41:47]

Maybe we should have a default implementation that returns false, to avoid lots
of the boilerplate overrides in this CL.

[lfg, 2016/07/07 20:17:35]

Done. I had that before, but clang complained about non-empty functions not
being allowed in headers -- but I just realized that there's also a .cc
implementation for RenderWidgetHostDelegate.

+
   // Called when the widget has sent a compositor proto.  This is used in Btlimp
   // mode with the RemoteChannel compositor.
   virtual void ForwardCompositorProto(RenderWidgetHostImpl* render_widget_host,
                                       const std::vector<uint8_t>& proto) {}
 
   // Called when the visibility of the RenderFrameProxyHost in outter
   // WebContents changes. This method is only called on an inner WebContents and
   // will eventually notify all the RenderWidgetHostViews belonging to that
   // WebContents.
   virtual void OnRenderFrameProxyVisibilityChanged(bool visible) {}
 
   // Update the renderer's cache of the screen rect of the view and window.
   virtual void SendScreenRects() {}
 
   // Notifies that the main frame in the renderer has performed the first paint
   // after a navigation.
   virtual void OnFirstPaintAfterLoad(RenderWidgetHostImpl* render_widget_host) {
   }
 
   // Returns the TextInputManager tracking text input state.
   virtual TextInputManager* GetTextInputManager();
 
  protected:
   virtual ~RenderWidgetHostDelegate() {}
 };
 
 }  // namespace content
 
 #endif  // CONTENT_BROWSER_RENDERER_HOST_RENDER_WIDGET_HOST_DELEGATE_H_