Part 1/3 (compositor) of adding with device scale factor to transport surfaces

cc/test/pixel_test.cc

Index: cc/test/pixel_test.cc
diff --git a/cc/test/pixel_test.cc b/cc/test/pixel_test.cc
index a191401d8682263863eb3364abaf37508d1af156..f648c7b9c2447e77e00d857303aba3c629f3591f 100644
--- a/cc/test/pixel_test.cc
+++ b/cc/test/pixel_test.cc
@@ -29,6 +29,9 @@ class PixelTest::PixelTestRendererClient : public RendererClient {
   virtual gfx::Size DeviceViewportSize() const OVERRIDE {
     return device_viewport_size_;
   }
+  virtual float DeviceScaleFactor() const OVERRIDE {
+    return 1.f;
+  }
   virtual const LayerTreeSettings& Settings() const OVERRIDE {
     return settings_;
   }