[Aura] Fix for a flash of black frame when resizing with the new resize logic.

content/browser/renderer_host/render_widget_host_view_aura.cc

 // 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_aura.h"
 
 #include "base/bind.h"
 #include "base/bind_helpers.h"
 #include "base/command_line.h"
 #include "base/debug/trace_event.h"
@@ skipping 740 matching lines @@
     HWND parent = root_window->GetAcceleratedWidget();
     LPARAM lparam = reinterpret_cast<LPARAM>(this);
 
     EnumChildWindows(parent, HideWindowsCallback, lparam);
   }
 #endif
 }
 
 void RenderWidgetHostViewAura::SetSize(const gfx::Size& size) {
   SetBounds(gfx::Rect(window_->bounds().origin(), size));
+  previous_damage_.op(RectToSkIRect(gfx::Rect(size)), SkRegion::kUnion_Op);

[piman, 2013/04/09 00:11:49]

Why is this needed?
When we resize, the new frame should have full damage. We DCHECK for it. So the
previous damage should not have any effect.

 }
 
 void RenderWidgetHostViewAura::SetBounds(const gfx::Rect& rect) {
   if (window_->bounds().size() != rect.size() &&
       host_->is_accelerated_compositing_active()) {
     aura::RootWindow* root_window = window_->GetRootWindow();
     ui::Compositor* compositor = root_window ?
         root_window->compositor() : NULL;
     if (root_window && compositor) {
       // Listen to changes in the compositor lock state.
@@ skipping 2033 matching lines @@
     RenderWidgetHost* widget) {
   return new RenderWidgetHostViewAura(widget);
 }
 
 // static
 void RenderWidgetHostViewPort::GetDefaultScreenInfo(WebScreenInfo* results) {
   GetScreenInfoForWindow(results, NULL);
 }
 
 }  // namespace content