Clear page display after navigation if no rendered output arrives

content/browser/renderer_host/render_widget_host_view_base.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_VIEW_BASE_H_
 #define CONTENT_BROWSER_RENDERER_HOST_RENDER_WIDGET_HOST_VIEW_BASE_H_
 
 #include <string>
 #include <vector>
 
@@ skipping 146 matching lines @@
   virtual gfx::Point AccessibilityOriginInScreen(const gfx::Rect& bounds);
   virtual gfx::AcceleratedWidget AccessibilityGetAcceleratedWidget();
   virtual gfx::NativeViewAccessible AccessibilityGetNativeViewAccessible();
 
   // Informs that the focused DOM node has changed.
   virtual void FocusedNodeChanged(bool is_editable_node) {}
 
   virtual void OnSwapCompositorFrame(uint32 output_surface_id,
                                      scoped_ptr<cc::CompositorFrame> frame) {}
 
+  virtual void ClearCompositorFrame() {}

[Charlie Reis, 2015/09/14 20:54:55]

Should this ever be left unimplemented, or should we make it pure virtual? 
Seems like it's a potential security issue to have some RHWVs that leave it as a
no-op.

[kenrb, 2015/09/14 21:29:36]

RenderWidgetHostViewChildFrame and RenderWidgetHostViewGuest do not implement
it, because the URL of their content is not displayed in the omnibar.

[Charlie Reis, 2015/09/14 21:40:18]

One option would be to put an empty implementation in
RenderWidgetHostViewChildFrame (inherited by RWHVG) but still leave it pure
virtual here, so that future platform subclasses have to implement it.  In the
future, it seems more likely that we'll add more platform subclasses than more
"subframe" subclasses.

I think that might be worthwhile, but I'll defer to you if there's a reason not
to.

[kenrb, 2015/09/15 15:25:41]

This makes sense. I've made the change.

+
   // Because the associated remote WebKit instance can asynchronously
   // prevent-default on a dispatched touch event, the touch events are queued in
   // the GestureRecognizer until invocation of ProcessAckedTouchEvent releases
   // it to be consumed (when |ack_result| is NOT_CONSUMED OR NO_CONSUMER_EXISTS)
   // or ignored (when |ack_result| is CONSUMED).
   virtual void ProcessAckedTouchEvent(const TouchEventWithLatencyInfo& touch,
                                       InputEventAckState ack_result) {}
 
   virtual void DidOverscroll(const DidOverscrollParams& params) {}
 
@@ skipping 252 matching lines @@
   base::OneShotTimer<RenderWidgetHostViewBase> flush_input_timer_;
 
   base::WeakPtrFactory<RenderWidgetHostViewBase> weak_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(RenderWidgetHostViewBase);
 };
 
 }  // namespace content
 
 #endif  // CONTENT_BROWSER_RENDERER_HOST_RENDER_WIDGET_HOST_VIEW_BASE_H_