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

content/renderer/render_widget.cc

Index: content/renderer/render_widget.cc
diff --git a/content/renderer/render_widget.cc b/content/renderer/render_widget.cc
index 425d943e846afe23eeee68090ece402399309bd5..60fbd389fbee93d39b5ba7daae41ef0e689e998b 100644
--- a/content/renderer/render_widget.cc
+++ b/content/renderer/render_widget.cc
@@ -321,6 +321,7 @@ bool RenderWidget::OnMessageReceived(const IPC::Message& message) {
     IPC_MESSAGE_HANDLER(ViewMsg_ImeBatchStateChanged, OnImeBatchStateChanged)
     IPC_MESSAGE_HANDLER(ViewMsg_ShowImeIfNeeded, OnShowImeIfNeeded)
 #endif
+    IPC_MESSAGE_HANDLER(ViewMsg_Snapshot, OnSnapshot)
     IPC_MESSAGE_UNHANDLED(handled = false)
   IPC_END_MESSAGE_MAP()
   return handled;
@@ -1820,6 +1821,50 @@ void RenderWidget::OnPaintAtSize(const TransportDIB::Handle& dib_handle,
   Send(new ViewHostMsg_PaintAtSize_ACK(routing_id_, tag, bounds.size()));
 }
 
+void RenderWidget::OnSnapshot(const gfx::Rect& src_subrect) {
+  SkBitmap snapshot;
+
+  if (OnSnapshotHelper(src_subrect, &snapshot)) {
+    Send(new ViewHostMsg_Snapshot(routing_id(), true, snapshot));
+  } else {
+    Send(new ViewHostMsg_Snapshot(routing_id(), false, SkBitmap()));
+  }
+}
+
+bool RenderWidget::OnSnapshotHelper(const gfx::Rect& src_subrect,
+                                    SkBitmap* snapshot) {
+  base::TimeTicks beginning_time = base::TimeTicks::Now();
+
+  if (!webwidget_ || src_subrect.IsEmpty())
+    return false;
+
+  gfx::Rect viewport_size = gfx::IntersectRects(
+      src_subrect, gfx::Rect(physical_backing_size_));
+
+  skia::RefPtr<SkCanvas> canvas = skia::AdoptRef(
+      skia::CreatePlatformCanvas(viewport_size.width(),
+                                 viewport_size.height(),
+                                 true,
+                                 NULL,
+                                 skia::RETURN_NULL_ON_FAILURE));
+  if (!canvas.get())
+    return false;
+
+  canvas->save();
+  webwidget_->layout();
+
+  PaintRect(viewport_size, viewport_size.origin(), canvas.get());
+  canvas->restore();
+
+  const SkBitmap& bitmap = skia::GetTopDevice(*canvas)->accessBitmap(false);
+  if (!bitmap.copyTo(snapshot, SkBitmap::kARGB_8888_Config))
+    return false;
+
+  UMA_HISTOGRAM_TIMES("Renderer4.Snapshot",
+                      base::TimeTicks::Now() - beginning_time);
+  return true;
+}
+
 void RenderWidget::OnRepaint(const gfx::Size& size_to_paint) {
   // During shutdown we can just ignore this message.
   if (!webwidget_)