Make RenderWidgetHostViewAura::CopyFromCompositingSurface readback layer

ui/compositor/layer.cc

Index: ui/compositor/layer.cc
diff --git a/ui/compositor/layer.cc b/ui/compositor/layer.cc
index e378ea85c2bde485deada82740b422fdbdef97a3..d0b328d36fd3a91dbb0351d8c8facbbce12c2023 100644
--- a/ui/compositor/layer.cc
+++ b/ui/compositor/layer.cc
@@ -15,6 +15,7 @@
 #include "cc/layers/delegated_renderer_layer.h"
 #include "cc/layers/solid_color_layer.h"
 #include "cc/layers/texture_layer.h"
+#include "cc/output/copy_output_request.h"
 #include "cc/output/delegated_frame_data.h"
 #include "cc/output/filter_operation.h"
 #include "cc/output/filter_operations.h"
@@ -625,6 +626,10 @@ void Layer::OnDeviceScaleFactorChanged(float device_scale_factor) {
     layer_mask_->OnDeviceScaleFactorChanged(device_scale_factor);
 }
 
+void Layer::RequestCopyOfOutput(scoped_ptr<cc::CopyOutputRequest> request) {
+  cc_layer_->RequestCopyOfOutput(request.Pass());
+}
+
 void Layer::PaintContents(SkCanvas* sk_canvas,
                           gfx::Rect clip,
                           gfx::RectF* opaque) {