Support browser side thumbnailing for GPU composited pages on Windows.

content/browser/renderer_host/render_widget_host_view_win.cc

Index: content/browser/renderer_host/render_widget_host_view_win.cc
diff --git a/content/browser/renderer_host/render_widget_host_view_win.cc b/content/browser/renderer_host/render_widget_host_view_win.cc
index 9f598b713d8a7d0f67a5ca4ff62b0467a244a20a..8fb17f6d329b58d19e89bae9f9bd3b5d0b1acd6a 100644
--- a/content/browser/renderer_host/render_widget_host_view_win.cc
+++ b/content/browser/renderer_host/render_widget_host_view_win.cc
@@ -908,6 +908,29 @@ void RenderWidgetHostViewWin::SetBackground(const SkBitmap& background) {
   render_widget_host_->SetBackground(background);
 }
 
+bool RenderWidgetHostViewWin::CopyFromCompositingSurface(
+      const gfx::Size& size,
+      skia::PlatformCanvas* output) {
+  if (!accelerated_surface_.get())
+    return false;
+
+  if (size.IsEmpty())
+    return false;
+
+  std::vector<unsigned char> pixels(4 * size.GetArea());
+  if(!accelerated_surface_->CopyTo(size, &pixels))
+    return false;
+
+  SkBitmap bitmap;
+  bitmap.setConfig(SkBitmap::kARGB_8888_Config, size.width(), size.height());
+  bitmap.setPixels(&pixels[0]);
+
+  if (!output->initialize(size.width(), size.height(), true))
+    return false;
+  output->writePixels(bitmap, 0, 0);

[vangelis, 2012/03/08 17:34:35]

Is it possible to call accelerated_surface_->CopyTo() directly onto the output
canvas' pixels to avoid this copy? 

[mazda, 2012/03/10 07:51:37]

I changed AccceleratedSurface::CopyTo to take void* as an argument following
apatrick's comment, so now it's possible to pass the raw pointer of SkBitmap in
this PlatformCanvas. I modified the code that way.

+  return true;
+}
+
 void RenderWidgetHostViewWin::UnhandledWheelEvent(
     const WebKit::WebMouseWheelEvent& event) {
 }