Use correct favicon scale factor on Android.

ui/gfx/screen_android.cc

 // Copyright (c) 2012 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.
 
 #include "ui/gfx/screen.h"
 
 #include "base/logging.h"
+#include "ui/gfx/android/device_display_info.h"
 #include "ui/gfx/display.h"
+#include "ui/gfx/size_conversions.h"
 
 namespace gfx {
 
 class ScreenAndroid : public Screen {
  public:
   ScreenAndroid() {}
 
   bool IsDIPEnabled() OVERRIDE {
     return true;
   }
 
   gfx::Point GetCursorScreenPoint() OVERRIDE {
     return gfx::Point();
   }
 
   gfx::NativeWindow GetWindowAtCursorScreenPoint() OVERRIDE {
     NOTIMPLEMENTED();
     return NULL;
   }
 
   gfx::Display GetPrimaryDisplay() const OVERRIDE {
-    NOTIMPLEMENTED() << "crbug.com/117839 tracks implementation";
-    return gfx::Display(0, gfx::Rect(0, 0, 1, 1));
+    gfx::DeviceDisplayInfo device_info;
+    const float device_scale_factor = device_info.GetDIPScale();
+    const gfx::Rect bounds_in_pixels =
+        gfx::Rect(
+            device_info.GetDisplayWidth(),
+            device_info.GetDisplayHeight());
+    const gfx::Rect bounds_in_dip =
+        gfx::Rect(gfx::ToCeiledSize(gfx::ScaleSize(
+            bounds_in_pixels.size(), 1.0f / device_scale_factor)));
+    gfx::Display display(0, bounds_in_dip);
+    display.set_device_scale_factor(device_scale_factor);
+    return display;
   }
 
   gfx::Display GetDisplayNearestWindow(gfx::NativeView view) const OVERRIDE {
     return GetPrimaryDisplay();
   }
 
   gfx::Display GetDisplayNearestPoint(const gfx::Point& point) const OVERRIDE {
     return GetPrimaryDisplay();
   }
 
@@ skipping 16 matching lines @@
 
  private:
   DISALLOW_COPY_AND_ASSIGN(ScreenAndroid);
 };
 
 Screen* CreateNativeScreen() {
   return new ScreenAndroid;
 }
 
 }  // namespace gfx