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

content/browser/compositor/mus_browser_compositor_output_surface.cc

Index: content/browser/compositor/mus_browser_compositor_output_surface.cc
diff --git a/content/browser/compositor/mus_browser_compositor_output_surface.cc b/content/browser/compositor/mus_browser_compositor_output_surface.cc
index 1b7a30b3ffc34254fbe5db8432b414ce54bcc6d4..d0ab5594967c6f4dd7f0837fbfe7d5a72b16d4e5 100644
--- a/content/browser/compositor/mus_browser_compositor_output_surface.cc
+++ b/content/browser/compositor/mus_browser_compositor_output_surface.cc
@@ -29,12 +29,14 @@ MusBrowserCompositorOutputSurface::MusBrowserCompositorOutputSurface(
     scoped_refptr<ui::CompositorVSyncManager> vsync_manager,
     cc::SyntheticBeginFrameSource* begin_frame_source,
     std::unique_ptr<display_compositor::CompositorOverlayCandidateValidator>
-        overlay_candidate_validator)
+        overlay_candidate_validator,
+    float device_scale_factor)
     : GpuBrowserCompositorOutputSurface(std::move(context),
                                         std::move(vsync_manager),
                                         begin_frame_source,
                                         std::move(overlay_candidate_validator)),
-      ui_window_(window) {
+      ui_window_(window),
+      device_scale_factor_(device_scale_factor) {
   ui_compositor_frame_sink_ = ui_window_->RequestCompositorFrameSink(
       ui::mojom::CompositorFrameSinkType::DEFAULT, context,
       gpu_memory_buffer_manager);
@@ -48,12 +50,14 @@ MusBrowserCompositorOutputSurface::MusBrowserCompositorOutputSurface(
     scoped_refptr<ui::CompositorVSyncManager> vsync_manager,
     cc::SyntheticBeginFrameSource* begin_frame_source,
     std::unique_ptr<display_compositor::CompositorOverlayCandidateValidator>
-        overlay_candidate_validator)
+        overlay_candidate_validator,
+    float device_scale_factor)
     : GpuBrowserCompositorOutputSurface(std::move(context),
                                         std::move(vsync_manager),
                                         begin_frame_source,
                                         std::move(overlay_candidate_validator)),
-      window_(window) {
+      window_(window),
+      device_scale_factor_(device_scale_factor) {
   aura::WindowPortMus* window_port = aura::WindowPortMus::Get(window_);
   DCHECK(window_port);
   compositor_frame_sink_ = window_port->RequestCompositorFrameSink(
@@ -69,6 +73,7 @@ void MusBrowserCompositorOutputSurface::SwapBuffers(
   const gfx::Rect bounds = ui_window_ ? gfx::Rect(ui_window_->bounds().size())
                                       : gfx::Rect(window_->bounds().size());
   cc::CompositorFrame ui_frame;
+  ui_frame.metadata.device_scale_factor = device_scale_factor_;

[danakj, 2016/12/06 22:44:27]

What if the device scale changes? It's not fixed for the life of the output
surface. Granted this whole class needs to go away and should not actually ship
to users.. but are you okay with this cuz I don't see it documented in TODOs or
anything like that.

[riajiang, 2016/12/15 18:14:41]

Changed to get the device_scale_factor from the display for window_
(aura::Window) which should be updated when dsf changes.

   ui_frame.metadata.latency_info = std::move(frame.latency_info);
   // Reset latency_info to known empty state after moving contents.
   frame.latency_info.clear();