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

cc/ipc/display_compositor.mojom

 // Copyright 2016 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 module cc.mojom;
 
 import "cc/ipc/frame_sink_id.mojom";
 import "cc/ipc/mojo_compositor_frame_sink.mojom";
 import "cc/ipc/surface_id.mojom";
 import "cc/ipc/surface_sequence.mojom";
@@ skipping 30 matching lines @@
 };
 
 // The DisplayCompositorClient interface is implemented by the Display
 // Compositor Host, a stable, and privileged peer service to the display
 // compositor. The display compositor host is either the browser process in
 // Chrome or the window server process.
 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);
 };