Use correct favicon scale factor on Android.

ui/gfx/screen_android.cc

Index: ui/gfx/screen_android.cc
diff --git a/ui/gfx/screen_android.cc b/ui/gfx/screen_android.cc
index a80582e077d22e1ff373c70f50f66cec6a534778..0da3f250fb144e579b92e5642c4b638ae528a709 100644
--- a/ui/gfx/screen_android.cc
+++ b/ui/gfx/screen_android.cc
@@ -5,7 +5,9 @@
 #include "ui/gfx/screen.h"
 
 #include "base/logging.h"
+#include "ui/gfx/android/device_info.h"
 #include "ui/gfx/display.h"
+#include "ui/gfx/size_conversions.h"
 
 namespace gfx {
 
@@ -14,7 +16,7 @@ class ScreenAndroid : public Screen {
   ScreenAndroid() {}
 
   bool IsDIPEnabled() OVERRIDE {
-    return false;
+    return true;
   }
 
   gfx::Point GetCursorScreenPoint() OVERRIDE {
@@ -27,8 +29,18 @@ class ScreenAndroid : public Screen {
   }
 
   gfx::Display GetPrimaryDisplay() const OVERRIDE {
-    NOTIMPLEMENTED() << "crbug.com/117839 tracks implementation";
-    return gfx::Display(0, gfx::Rect(0, 0, 1, 1));
+    gfx::DeviceInfo 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::ToRoundedSize(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 {