Set device scale factor in CompositorFrame and scale frame size in WS.

cc/ipc/display_compositor.mojom

Index: cc/ipc/display_compositor.mojom
diff --git a/cc/ipc/display_compositor.mojom b/cc/ipc/display_compositor.mojom
index d8fab7a6763bd5a70fb02084d7af69a7310269b0..13eb5230180cb0e3d78f913f25f237fbd2fe016f 100644
--- a/cc/ipc/display_compositor.mojom
+++ b/cc/ipc/display_compositor.mojom
@@ -48,6 +48,6 @@ interface DisplayCompositorClient {
   // Called by the display compositor immediately upon receiving a
   // CompositorFrame with a new SurfaceId for the first time.
   OnSurfaceCreated(cc.mojom.SurfaceId surface_id,
-                   gfx.mojom.Size frame_size,
+                   gfx.mojom.Size frame_size_in_dip,

[kylechar, 2016/12/05 14:46:11]

This is comes via SurfaceManager like so:

SurfaceManager::SurfaceCreated()
DisplayCompositor::OnSurfaceCreated()
DisplayCompositorClient::OnSurfaceCreated()

SurfaceManager operates in PP, so frame_size will be in PP.

                    float device_scale_factor);
 };