Remove "upgrading to 2x DSF for lower UI scale when 2x resoruces are available" option

BUG=None

Review URL: https://codereview.chromium.org/579053002

Cr-Commit-Position: refs/heads/master@{#295509}

4 files changed, 8 insertions, 68 deletions

diff --git a/ash/display/display_info.cc b/ash/display/display_info.cc
index 6a117b0..61432f6 100644
--- a/ash/display/display_info.cc
+++ b/ash/display/display_info.cc
@@ -23,9 +23,6 @@
 namespace ash {
 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-// TODO(oshima): This feature is obsolete.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|.
@@ -46,7 +43,7 @@ bool GetDisplayBounds(
   return false;
 }
 
-}
+}  // namespace
 
 DisplayMode::DisplayMode()
     : refresh_rate(0.0f),
@@ -86,9 +83,6 @@ DisplayInfo DisplayInfo::CreateFromSpec(const std::string& spec) {
 }
 
 // static
-void DisplayInfo::SetAllowUpgradeToHighDPI(bool enable) {
-  allow_upgrade_to_high_dpi = enable;
-}
 
 // static
 void DisplayInfo::SetUse125DSFForUIScaling(bool enable) {
@@ -292,26 +286,16 @@ 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;
-  } else if (device_scale_factor_ == configured_ui_scale_) {
+  if (device_scale_factor_ == configured_ui_scale_)
     return 1.0f;
-  }
   return device_scale_factor_;
 }
 
 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;
-  } else if (device_scale_factor_ == configured_ui_scale_) {
+  if (device_scale_factor_ == configured_ui_scale_)
     return 1.0f;
-  }
   return configured_ui_scale_;
 }
 
diff --git a/ash/display/display_info.h b/ash/display/display_info.h
index a7db7f0..5598273 100644
--- a/ash/display/display_info.h
+++ b/ash/display/display_info.h
@@ -89,11 +89,6 @@ class ASH_EXPORT DisplayInfo {
   DisplayInfo(int64 id, const std::string& name, bool has_overscan);
   ~DisplayInfo();
 
-  // When this is set to true, Chrome switches High DPI when lower UI scale
-  // (<1.0f) is specified on 1x device to make UI sharp, e.g, upgrade 0.6
-  // 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.
@@ -148,10 +143,12 @@ class ASH_EXPORT DisplayInfo {
   // display that chrome sees. This can be different from one obtained
   // from dispaly or one specified by a user in following situation.
   // 1) DSF is 2.0f and UI scale is 2.0f. (Returns 1.0f and 1.0f respectiely)
-  // 2) Lower UI scale (< 1.0) is specified on 1.0f DSF device
-  // when 2x resources is available. (Returns 2.0f DSF + 1.2f UI scale
-  // for 1.0DSF + 0.6 UI scale).
+  // 2) A user specified 0.8x on the device that has 1.25 DSF. 1.25 DSF device
+  //    uses 1.0f DFS unless 0.8x UI scaling is specified.
   float GetEffectiveDeviceScaleFactor() const;
+
+  // Returns the ui scale used for the device scale factor. This
+  // return 1.0f if the ui scale and dsf are both set to 2.0.
   float GetEffectiveUIScale() const;
 
   // Copy the display info except for fields that can be modified by a
diff --git a/ash/display/display_manager.cc b/ash/display/display_manager.cc
index 291dddb..4cec2ea 100644
--- a/ash/display/display_manager.cc
+++ b/ash/display/display_manager.cc
@@ -25,8 +25,6 @@
 #include "base/strings/utf_string_conversions.h"
 #include "grit/ash_strings.h"
 #include "ui/base/l10n/l10n_util.h"
-#include "ui/base/layout.h"
-#include "ui/base/resource/resource_bundle.h"
 #include "ui/gfx/display.h"
 #include "ui/gfx/display_observer.h"
 #include "ui/gfx/font_render_params.h"
diff --git a/ash/display/display_manager_unittest.cc b/ash/display/display_manager_unittest.cc
index 36c75f9..311c4de 100644
--- a/ash/display/display_manager_unittest.cc
+++ b/ash/display/display_manager_unittest.cc
@@ -1065,45 +1065,6 @@ TEST_F(DisplayManagerTest, UIScaleWithDisplayMode) {
       display_manager()->GetActiveModeForDisplayId(display_id)));
 }
 
-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());
-}
 
 TEST_F(DisplayManagerTest, Use125DSFRorUIScaling) {
   int64 display_id = Shell::GetScreen()->GetPrimaryDisplay().id();