Allow CopyFromBackingStore to fallback to copying from the renderer side if the accelerated surface…

content/browser/renderer_host/render_widget_host_impl.h

Index: content/browser/renderer_host/render_widget_host_impl.h
diff --git a/content/browser/renderer_host/render_widget_host_impl.h b/content/browser/renderer_host/render_widget_host_impl.h
index 9485aa8828ef69db3d986761f7a237dbcc8dea42..834e776118f011d5893d60933c0a5fddb31c5be4 100644
--- a/content/browser/renderer_host/render_widget_host_impl.h
+++ b/content/browser/renderer_host/render_widget_host_impl.h
@@ -10,6 +10,7 @@
 #include <map>
 #include <queue>
 #include <string>
+#include <utility>
 #include <vector>
 
 #include "base/callback.h"
@@ -450,6 +451,13 @@ class CONTENT_EXPORT RenderWidgetHostImpl : virtual public RenderWidgetHost,
   // suppress_next_char_events_.
   void SuppressNextCharEvents();
 
+  // Grab snapshot from renderer side. This can be used when copying from
+  // browser side might fail due to buggy drivers or other issues.

[Sam Kerner (Chrome), 2013/03/18 13:49:51]

Unless something changed, this should note that copying from the browser side
might fail because the browser side's cache has limited resources, and
intentionally discards images of tabs that are not visible and unused for a
while.

[justinlin, 2013/03/18 18:10:01]

I mentioned when the backing store is not available, which is more or less the
same issue.

As far as I can tell (after looking through the platform specific
CopyFromBackingStore's), it can't actually fail in the copy unless there's some
Skia issue.

+  void GetSnapshotFromRenderer(
+      const gfx::Rect& src_subrect,
+      const gfx::Size& dst_size,
+      const base::Callback<void(bool, const SkBitmap&)>& callback);
+
  protected:
   virtual RenderWidgetHostImpl* AsRenderWidgetHostImpl() OVERRIDE;
 
@@ -602,6 +610,7 @@ class CONTENT_EXPORT RenderWidgetHostImpl : virtual public RenderWidgetHost,
   void OnWindowlessPluginDummyWindowDestroyed(
       gfx::NativeViewId dummy_activation_window);
 #endif
+  void OnSnapshot(bool success, const SkBitmap& bitmap);
 
   // Called (either immediately or asynchronously) after we're done with our
   // BackingStore and can send an ACK to the renderer so it can paint onto it
@@ -857,6 +866,10 @@ class CONTENT_EXPORT RenderWidgetHostImpl : virtual public RenderWidgetHost,
   scoped_ptr<GestureEventFilter> gesture_event_filter_;
   scoped_ptr<OverscrollController> overscroll_controller_;
 
+  typedef std::pair<gfx::Size, base::Callback<void(bool, const SkBitmap&)> >
+      PendingSnapshotInfo;
+  std::queue<PendingSnapshotInfo> pending_snapshots_;
+
 #if defined(OS_WIN)
   std::list<HWND> dummy_windows_for_activation_;
 #endif