Support browser side thumbnailing for GPU composited pages on Windows.

content/browser/renderer_host/render_widget_host_impl.cc

Index: content/browser/renderer_host/render_widget_host_impl.cc
diff --git a/content/browser/renderer_host/render_widget_host_impl.cc b/content/browser/renderer_host/render_widget_host_impl.cc
index 9136aebafcd00d4b228b8545425c43ffc6055f76..892702eefecc37edbea949e51688c845c3f689b7 100644
--- a/content/browser/renderer_host/render_widget_host_impl.cc
+++ b/content/browser/renderer_host/render_widget_host_impl.cc
@@ -32,6 +32,7 @@
 #include "content/public/browser/user_metrics.h"
 #include "content/public/common/content_switches.h"
 #include "content/public/common/result_codes.h"
+#include "skia/ext/platform_canvas.h"
 #include "third_party/WebKit/Source/WebKit/chromium/public/WebCompositionUnderline.h"
 #include "ui/base/keycodes/keyboard_codes.h"
 #include "webkit/glue/webcursor.h"
@@ -498,10 +499,24 @@ bool RenderWidgetHostImpl::CopyFromBackingStore(skia::PlatformCanvas* output) {
   if (!backing_store)
     return false;
 
+  TRACE_EVENT0("browser", "RenderWidgetHostImpl::CopyFromBackingStore");
   return backing_store->CopyFromBackingStore(
       gfx::Rect(backing_store->size()), output);
 }
 
+bool RenderWidgetHostImpl::CopyFromCompositingSurface(
+    const gfx::Size& size,
+    skia::PlatformCanvas* output) {
+  if (!is_accelerated_compositing_active_)
+    return false;
+
+  if (!view_)
+    return false;
+
+  TRACE_EVENT0("browser", "RenderWidgetHostImpl::CopyFromCompositingSurface");
+  return view_->CopyFromCompositingSurface(size, output);
+}
+
 #if defined(TOOLKIT_GTK)
 bool RenderWidgetHostImpl::CopyFromBackingStoreToGtkWindow(
     const gfx::Rect& dest_rect, GdkWindow* target) {