Use the source display's pixel size as a mirror window's size.

ash/display/root_window_transformers_unittest.cc

Index: ash/display/root_window_transformers_unittest.cc
diff --git a/ash/ash_root_window_transformer_unittest.cc b/ash/display/root_window_transformers_unittest.cc
similarity index 98%
rename from ash/ash_root_window_transformer_unittest.cc
rename to ash/display/root_window_transformers_unittest.cc
index 5bca069972c91ad57bb297b0c1b8d6b62b4796a1..7d0fce5473db09219dc9a701385171bc845f5fb6 100644
--- a/ash/ash_root_window_transformer_unittest.cc
+++ b/ash/display/root_window_transformers_unittest.cc
@@ -2,7 +2,7 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-#include"ash/ash_root_window_transformer.h"
+#include "ash/display/root_window_transformers.h"
 
 #include "ash/display/display_controller.h"
 #include "ash/display/display_info.h"
@@ -291,8 +291,8 @@ TEST_F(AshRootWindowTransformerTest, MAYBE_TouchScaleAndMagnify) {
   generator.PressMoveAndReleaseTouchTo(50, 50);
   // Default test touches have radius_x/y = 1.0, with device scale
   // factor = 2, the scaled radius_x/y should be 0.5.
-  EXPECT_FLOAT_EQ(0.2, event_handler.touch_radius_x());
-  EXPECT_FLOAT_EQ(0.2, event_handler.touch_radius_y());
+  EXPECT_FLOAT_EQ(0.2f, event_handler.touch_radius_x());
+  EXPECT_FLOAT_EQ(0.2f, event_handler.touch_radius_y());
 
   generator.ScrollSequence(gfx::Point(0,0),
                            base::TimeDelta::FromMilliseconds(100),