Add ability to copy unscaled output pixels.

content/browser/renderer_host/render_widget_host_view_base.h

Index: content/browser/renderer_host/render_widget_host_view_base.h
diff --git a/content/browser/renderer_host/render_widget_host_view_base.h b/content/browser/renderer_host/render_widget_host_view_base.h
index 5156ca683f82ac9ddc695796becc8bed30d52633..2b41467c5d449fad7e20293103e6ef4f9c55aa50 100644
--- a/content/browser/renderer_host/render_widget_host_view_base.h
+++ b/content/browser/renderer_host/render_widget_host_view_base.h
@@ -256,10 +256,12 @@ class CONTENT_EXPORT RenderWidgetHostViewBase : public RenderWidgetHostView,
   // Copies the contents of the compositing surface, providing a new SkBitmap
   // result via an asynchronously-run |callback|. |src_subrect| is specified in
   // layer space coordinates for the current platform (e.g., DIP for Aura/Mac,
-  // physical for Android), and is the region to be copied from this view. The
-  // copy is then scaled to a SkBitmap of size |dst_size|. |callback| is run
-  // with true on success, false otherwise. A smaller region than |src_subrect|
-  // may be copied if the underlying surface is smaller than |src_subrect|.
+  // physical for Android), and is the region to be copied from this view. When
+  // |src_subrect| is empty then the whole surface will be copied. The copy is
+  // then scaled to a SkBitmap of size |dst_size|. If |dst_size| is empty then
+  // output will be unscaled. |callback| is run with true on success,
+  // false otherwise. A smaller region than |src_subrect| may be copied
+  // if the underlying surface is smaller than |src_subrect|.
   virtual void CopyFromCompositingSurface(const gfx::Rect& src_subrect,
                                           const gfx::Size& dst_size,
                                           ReadbackRequestCallback& callback,