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_info.cc

 // Copyright (c) 2013 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 <stdio.h>
 #include <string>
 #include <vector>
 
 #include "ash/display/display_info.h"
 #include "base/logging.h"
 #include "base/strings/string_number_conversions.h"
 #include "base/strings/string_util.h"
 #include "base/strings/stringprintf.h"
 #include "ui/gfx/display.h"
 #include "ui/gfx/size_conversions.h"
 #include "ui/gfx/size_f.h"
 
 #if defined(OS_WIN)
 #include "ui/aura/window_tree_host.h"
 #include "ui/gfx/win/dpi.h"
 #endif
 
 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 // TODO(oshima): This feature is obsolete.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|.
 // Returns true when |bounds| is found.
 bool GetDisplayBounds(
     const std::string& spec, gfx::Rect* bounds, float* device_scale_factor) {
   int width = 0;
   int height = 0;
   int x = 0;
   int y = 0;
   if (sscanf(spec.c_str(), "%dx%d*%f",
              &width, &height, device_scale_factor) >= 2 ||
@@ skipping 43 matching lines @@
 DisplayInfo DisplayInfo::CreateFromSpec(const std::string& spec) {
   return CreateFromSpecWithID(spec, gfx::Display::kInvalidDisplayID);
 }
 
 // static
 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) {
   // Default bounds for a display.
   const int kDefaultHostWindowX = 200;
   const int kDefaultHostWindowY = 200;
   const int kDefaultHostWindowWidth = 1366;
   const int kDefaultHostWindowHeight = 768;
 
   // Use larger than max int to catch overflow early.
   static int64 synthesized_display_id = 2200000000LL;
@@ skipping 174 matching lines @@
   // |CreateFromSpec|.
 }
 
 void DisplayInfo::SetBounds(const gfx::Rect& new_bounds_in_native) {
   bounds_in_native_ = new_bounds_in_native;
   size_in_pixel_ = new_bounds_in_native.size();
   UpdateDisplaySize();
 }
 
 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_) {
     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_) {
     return 1.0f;
   }
   return configured_ui_scale_;
 }
 
 void DisplayInfo::UpdateDisplaySize() {
@@ skipping 75 matching lines @@
 }
 
 bool DisplayInfo::IsColorProfileAvailable(
     ui::ColorCalibrationProfile profile) const {
   return std::find(available_color_profiles_.begin(),
                    available_color_profiles_.end(),
                    profile) != available_color_profiles_.end();
 }
 
 }  // namespace ash