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

Disable high DPI assets for ui scaling. This will be removed in 39, after this change is landed.

BUG=413368

Review URL: https://codereview.chromium.org/578553002

Cr-Commit-Position: refs/heads/master@{#295209}

ash/display/display_controller.cc

@@ -636,7 +636,6 @@ void DisplayController::OnDisplayMetricsChanged(const gfx::Display& display,
   if (!(metrics & (DISPLAY_METRIC_BOUNDS | DISPLAY_METRIC_ROTATION |
                    DISPLAY_METRIC_DEVICE_SCALE_FACTOR)))
     return;
-
   const DisplayInfo& display_info =
       GetDisplayManager()->GetDisplayInfo(display.id());
   DCHECK(!display_info.bounds_in_native().IsEmpty());

ash/display/display_info.cc

@@ -26,6 +26,8 @@ namespace {
 // TODO(oshima): This feature is obsolete. Remove this after m38.
 bool allow_upgrade_to_high_dpi = false;
 
+bool use_125_dsf_for_ui_scaling = false;
+
 // Check the content of |spec| and fill |bounds| and |device_scale_factor|.
 // Returns true when |bounds| is found.
 bool GetDisplayBounds(
@@ -88,6 +90,11 @@ void DisplayInfo::SetAllowUpgradeToHighDPI(bool enable) {
   allow_upgrade_to_high_dpi = enable;
 }
 
+// static
+void DisplayInfo::SetUse125DSFForUIScaling(bool enable) {
+  use_125_dsf_for_ui_scaling = enable;
+}
+
 // static
 DisplayInfo DisplayInfo::CreateFromSpecWithID(const std::string& spec,
                                               int64 id) {
@@ -283,6 +290,9 @@ void DisplayInfo::SetBounds(const gfx::Rect& new_bounds_in_native) {
 }
 
 float DisplayInfo::GetEffectiveDeviceScaleFactor() const {
+  if (use_125_dsf_for_ui_scaling && device_scale_factor_ == 1.25f)
+    return (configured_ui_scale_ == 0.8f) ? 1.25f : 1.0f;
+
   if (allow_upgrade_to_high_dpi && configured_ui_scale_ < 1.0f &&
       device_scale_factor_ == 1.0f) {
     return 2.0f;
@@ -293,6 +303,9 @@ float DisplayInfo::GetEffectiveDeviceScaleFactor() const {
 }
 
 float DisplayInfo::GetEffectiveUIScale() const {
+  if (use_125_dsf_for_ui_scaling && device_scale_factor_ == 1.25f)
+    return (configured_ui_scale_ == 0.8f) ? 1.0f : configured_ui_scale_;
+
   if (allow_upgrade_to_high_dpi && configured_ui_scale_ < 1.0f &&
       device_scale_factor_ == 1.0f) {
     return configured_ui_scale_ * 2.0f;

ash/display/display_info.h

@@ -94,6 +94,11 @@ class ASH_EXPORT DisplayInfo {
   // scale on 1x DSF to 1.2 scale on 2x DSF.
   static void SetAllowUpgradeToHighDPI(bool enable);
 
+  // When this is set to true on the device whose internal display has
+  // 1.25 dsf, Chrome uses 1.0f as a default scale factor, and uses
+  // dsf 1.25 when UI scaling is set to 0.8f.
+  static void SetUse125DSFForUIScaling(bool enable);
+
   int64 id() const { return id_; }
 
   // The name of the display.

ash/display/display_manager.cc

@@ -168,10 +168,6 @@ DisplayManager::DisplayManager()
 #if defined(OS_CHROMEOS)
   change_display_upon_host_resize_ = !base::SysInfo::IsRunningOnChromeOS();
 #endif
-  DisplayInfo::SetAllowUpgradeToHighDPI(
-      ui::ResourceBundle::GetSharedInstance().GetMaxScaleFactor() ==
-      ui::SCALE_FACTOR_200P);
-
   gfx::Screen::SetScreenInstance(gfx::SCREEN_TYPE_ALTERNATE,
                                  screen_ash_.get());
   gfx::Screen* current_native =
@@ -252,6 +248,7 @@ bool DisplayManager::InitFromCommandLine() {
   for (vector<string>::const_iterator iter = parts.begin();
        iter != parts.end(); ++iter) {
     info_list.push_back(DisplayInfo::CreateFromSpec(*iter));
+    info_list.back().set_native(true);
   }
   MaybeInitInternalDisplay(info_list[0].id());
   if (info_list.size() > 1 &&
@@ -265,6 +262,7 @@ bool DisplayManager::InitFromCommandLine() {
 void DisplayManager::InitDefaultDisplay() {
   DisplayInfoList info_list;
   info_list.push_back(DisplayInfo::CreateFromSpec(std::string()));
+  info_list.back().set_native(true);
   MaybeInitInternalDisplay(info_list[0].id());
   OnNativeDisplaysChanged(info_list);
 }
@@ -276,7 +274,7 @@ void DisplayManager::InitFontParams() {
   const DisplayInfo& display_info =
       GetDisplayInfo(gfx::Display::InternalDisplayId());
   gfx::SetFontRenderParamsDeviceScaleFactor(
-      display_info.device_scale_factor());
+      display_info.GetEffectiveDeviceScaleFactor());
 #endif  // OS_CHROMEOS
 }
 

ash/display/display_manager_unittest.cc

@@ -1102,6 +1102,33 @@ TEST_F(DisplayManagerTest, UIScaleUpgradeToHighDPI) {
   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.
@@ -1474,6 +1501,16 @@ TEST_F(DisplayManagerFontTest, TextSubpixelPositioningWithDsf200External) {
   EXPECT_FALSE(IsTextSubpixelPositioningEnabled());
 }
 
+TEST_F(DisplayManagerFontTest,
+       TextSubpixelPositioningWithDsf125InternalWithScaling) {
+  DisplayInfo::SetUse125DSFForUIScaling(true);
+  FontTestHelper helper(1.25f, FontTestHelper::INTERNAL);
+  ASSERT_DOUBLE_EQ(
+      1.0f, Shell::GetScreen()->GetPrimaryDisplay().device_scale_factor());
+  EXPECT_FALSE(IsTextSubpixelPositioningEnabled());
+  DisplayInfo::SetUse125DSFForUIScaling(false);
+}
+
 #endif  // OS_CHROMEOS
 
 }  // namespace ash