Specify a default display UI scale to reset the zoom to

ash/test/display_manager_test_api.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/test/display_manager_test_api.h"
 
 #include <cstdarg>
 #include <vector>
 
 #include "ash/display/display_manager.h"
@@ skipping 26 matching lines @@
   for (std::vector<std::string>::const_iterator iter = parts.begin();
        iter != parts.end(); ++iter, ++index) {
     int64_t id = (index < list.size()) ? list[index].id()
                                        : display::Display::kInvalidDisplayID;
     display_info_list.push_back(
         display::ManagedDisplayInfo::CreateFromSpecWithID(*iter, id));
   }
   return display_info_list;
 }
 
+scoped_refptr<display::ManagedDisplayMode> GetDisplayModeForUIScale(
+    const display::ManagedDisplayInfo& info,
+    float ui_scale) {
+  const display::ManagedDisplayInfo::ManagedDisplayModeList& modes =
+      info.display_modes();
+  auto iter = std::find_if(
+      modes.begin(), modes.end(),
+      [ui_scale](const scoped_refptr<display::ManagedDisplayMode>& mode) {
+        return mode->ui_scale() == ui_scale;
+      });
+  if (iter == modes.end())
+    return scoped_refptr<display::ManagedDisplayMode>();
+  return *iter;
+}
+
 }  // namespace
 
 DisplayManagerTestApi::DisplayManagerTestApi(DisplayManager* display_manager)
     : display_manager_(display_manager) {}
 
 DisplayManagerTestApi::~DisplayManagerTestApi() {}
 
 void DisplayManagerTestApi::UpdateDisplay(const std::string& display_specs) {
   DisplayInfoList display_info_list =
       CreateDisplayInfoListFromString(display_specs, display_manager_);
@@ skipping 49 matching lines @@
     const std::vector<ui::ColorCalibrationProfile>& profiles) {
   display_manager_->display_info_[display_id].set_available_color_profiles(
       profiles);
 }
 
 const display::ManagedDisplayInfo&
 DisplayManagerTestApi::GetInternalManagedDisplayInfo(int64_t display_id) {
   return display_manager_->display_info_[display_id];
 }
 
+bool DisplayManagerTestApi::SetDisplayUIScale(int64_t id, float ui_scale) {
+  if (!display_manager_->IsActiveDisplayId(id) ||
+      !display::Display::IsInternalDisplayId(id)) {
+    return false;
+  }
+  const display::ManagedDisplayInfo& info =
+      display_manager_->GetDisplayInfo(id);
+
+  scoped_refptr<display::ManagedDisplayMode> mode =
+      GetDisplayModeForUIScale(info, ui_scale);
+  if (!mode)
+    return false;
+  return display_manager_->SetDisplayMode(id, mode);
+}
+
 ScopedDisable125DSFForUIScaling::ScopedDisable125DSFForUIScaling() {
   display::ManagedDisplayInfo::SetUse125DSFForUIScalingForTest(false);
 }
 
 ScopedDisable125DSFForUIScaling::~ScopedDisable125DSFForUIScaling() {
   display::ManagedDisplayInfo::SetUse125DSFForUIScalingForTest(true);
 }
 
 ScopedSetInternalDisplayId::ScopedSetInternalDisplayId(
     DisplayManager* display_manager,
@@ skipping 43 matching lines @@
   for (size_t i = 0; i < count; i++) {
     int64_t id = va_arg(args, int64_t);
     list.push_back(id);
   }
   display::SortDisplayIdList(&list);
   return list;
 }
 
 }  // namespace test
 }  // namespace ash