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

services/ui/ws/frame_generator_unittest.cc

Index: services/ui/ws/frame_generator_unittest.cc
diff --git a/services/ui/ws/frame_generator_unittest.cc b/services/ui/ws/frame_generator_unittest.cc
index 12630eb94916e5b838d37a611f76e94c7239497f..14f9e8d961dc17a015736223257e5eb6df5ceedb 100644
--- a/services/ui/ws/frame_generator_unittest.cc
+++ b/services/ui/ws/frame_generator_unittest.cc
@@ -84,6 +84,8 @@ void FrameGeneratorTest::SetUp() {
   PlatformDisplayInitParams init_params;
   frame_generator_ = base::MakeUnique<FrameGenerator>(
       frame_generator_delegate_.get(), root_window_.get());
+  frame_generator_->set_device_scale_factor(
+      init_params.metrics.device_scale_factor);

[Fady Samuel, 2016/12/15 18:27:51]

I would actually make the device_scale_factor a param on the constructor.

[riajiang, 2016/12/15 19:01:43]

We are also updating DSF in PlatformDisplayDefault::UpdateViewportMetrics which
is calling this set_..., does it make sense to just have this one setter and use
this when initializing DSF as well?

   InitWindow(root_window());
 }