Allow upgrading to 2x DSF for lower UI scale when 2x resoruces are available.

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/display/display_controller.h"
 #include "ash/display/display_layout_store.h"
 #include "ash/screen_util.h"
 #include "ash/shell.h"
@@ skipping 927 matching lines @@
   EXPECT_EQ(0.5f, GetDisplayInfoAt(0).configured_ui_scale());
 
   display_manager()->SetDisplayUIScale(display_id, 2.0f);
   EXPECT_EQ(2.0f, GetDisplayInfoAt(0).configured_ui_scale());
   EXPECT_EQ(1.0f, GetDisplayInfoAt(0).GetEffectiveUIScale());
   display = Shell::GetScreen()->GetPrimaryDisplay();
   EXPECT_EQ(1.0f, display.device_scale_factor());
   EXPECT_EQ("1280x850", display.bounds().size().ToString());
 }
 
+TEST_F(DisplayManagerTest, UIScaleUpgradeToHighDPI) {
+  int64 display_id = Shell::GetScreen()->GetPrimaryDisplay().id();
+  gfx::Display::SetInternalDisplayId(display_id);
+  UpdateDisplay("1920x1080");
+
+  DisplayInfo::SetAllowUpgradeToHighDPI(false);
+  display_manager()->SetDisplayUIScale(display_id, 1.125f);
+  EXPECT_EQ(1.0f, GetDisplayInfoAt(0).GetEffectiveDeviceScaleFactor());
+  EXPECT_EQ(1.125f, GetDisplayInfoAt(0).GetEffectiveUIScale());
+  EXPECT_EQ("2160x1215", 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());
+
+  DisplayInfo::SetAllowUpgradeToHighDPI(true);
+  display_manager()->SetDisplayUIScale(display_id, 1.125f);
+  EXPECT_EQ(1.0f, GetDisplayInfoAt(0).GetEffectiveDeviceScaleFactor());
+  EXPECT_EQ(1.125f, GetDisplayInfoAt(0).GetEffectiveUIScale());
+  EXPECT_EQ("2160x1215", GetDisplayForId(display_id).size().ToString());
+
+  display_manager()->SetDisplayUIScale(display_id, 0.5f);
+  EXPECT_EQ(2.0f, GetDisplayInfoAt(0).GetEffectiveDeviceScaleFactor());
+  EXPECT_EQ(1.0f, GetDisplayInfoAt(0).GetEffectiveUIScale());
+  EXPECT_EQ("960x540", GetDisplayForId(display_id).size().ToString());
+
+  // Upgrade only works on 1.0f DSF.
+  UpdateDisplay("1920x1080*2");
+  display_manager()->SetDisplayUIScale(display_id, 1.125f);
+  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());
+}
 
 #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) {
@@ skipping 265 matching lines @@
   DISALLOW_COPY_AND_ASSIGN(ScreenShutdownTest);
 };
 
 TEST_F(ScreenShutdownTest, ScreenAfterShutdown) {
   if (!SupportsMultipleDisplays())
     return;
   UpdateDisplay("500x300,800x400");
 }
 
 }  // namespace ash