Use DSF instead of UI scale if the native DSF is 1.25 and UI Scale is 0.8x (dsf=1.25 equivalent)

ash/display/display_manager_unittest.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 "ash/display/display_manager.h"
 
 #include "ash/ash_switches.h"
 #include "ash/display/display_controller.h"
 #include "ash/display/display_layout_store.h"
 #include "ash/screen_util.h"
@@ skipping 1084 matching lines @@
   EXPECT_EQ(2.0f, GetDisplayInfoAt(0).GetEffectiveDeviceScaleFactor());
   EXPECT_EQ(1.125f, GetDisplayInfoAt(0).GetEffectiveUIScale());
   EXPECT_EQ("1080x607", GetDisplayForId(display_id).size().ToString());
 
   display_manager()->SetDisplayUIScale(display_id, 0.5f);
   EXPECT_EQ(2.0f, GetDisplayInfoAt(0).GetEffectiveDeviceScaleFactor());
   EXPECT_EQ(0.5f, GetDisplayInfoAt(0).GetEffectiveUIScale());
   EXPECT_EQ("480x270", GetDisplayForId(display_id).size().ToString());
 }
 
+TEST_F(DisplayManagerTest, Use125DSFRorUIScaling) {
+  int64 display_id = Shell::GetScreen()->GetPrimaryDisplay().id();
+  gfx::Display::SetInternalDisplayId(display_id);
+  DisplayInfo::SetUse125DSFForUIScaling(true);
+
+  UpdateDisplay("1920x1080*1.25");
+  EXPECT_EQ(1.0f, GetDisplayInfoAt(0).GetEffectiveDeviceScaleFactor());
+  EXPECT_EQ(1.0f, GetDisplayInfoAt(0).GetEffectiveUIScale());
+
+  display_manager()->SetDisplayUIScale(display_id, 0.8f);
+  EXPECT_EQ(1.25f, GetDisplayInfoAt(0).GetEffectiveDeviceScaleFactor());
+  EXPECT_EQ(1.0f, GetDisplayInfoAt(0).GetEffectiveUIScale());
+  EXPECT_EQ("1536x864", GetDisplayForId(display_id).size().ToString());
+
+  display_manager()->SetDisplayUIScale(display_id, 0.5f);
+  EXPECT_EQ(1.0f, GetDisplayInfoAt(0).GetEffectiveDeviceScaleFactor());
+  EXPECT_EQ(0.5f, GetDisplayInfoAt(0).GetEffectiveUIScale());
+  EXPECT_EQ("960x540", GetDisplayForId(display_id).size().ToString());
+
+  display_manager()->SetDisplayUIScale(display_id, 1.25f);
+  EXPECT_EQ(1.0f, GetDisplayInfoAt(0).GetEffectiveDeviceScaleFactor());
+  EXPECT_EQ(1.25f, GetDisplayInfoAt(0).GetEffectiveUIScale());
+  EXPECT_EQ("2400x1350", GetDisplayForId(display_id).size().ToString());
+
+  DisplayInfo::SetUse125DSFForUIScaling(false);
+}
+
 #if defined(OS_WIN)
 // TODO(scottmg): RootWindow doesn't get resized on Windows
 // Ash. http://crbug.com/247916.
 #define MAYBE_UpdateMouseCursorAfterRotateZoom DISABLED_UpdateMouseCursorAfterRotateZoom
 #else
 #define MAYBE_UpdateMouseCursorAfterRotateZoom UpdateMouseCursorAfterRotateZoom
 #endif
 
 TEST_F(DisplayManagerTest, MAYBE_UpdateMouseCursorAfterRotateZoom) {
   // Make sure just rotating will not change native location.
@@ skipping 355 matching lines @@
 TEST_F(DisplayManagerFontTest, TextSubpixelPositioningWithDsf200External) {
   FontTestHelper helper(2.0f, FontTestHelper::EXTERNAL);
   ASSERT_DOUBLE_EQ(
       2.0f, Shell::GetScreen()->GetPrimaryDisplay().device_scale_factor());
   EXPECT_FALSE(IsTextSubpixelPositioningEnabled());
 }
 
 #endif  // OS_CHROMEOS
 
 }  // namespace ash