Specify a default display UI scale to reset the zoom to

ash/display/display_manager.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 <algorithm>
 #include <cmath>
 #include <limits>
 #include <map>
@@ skipping 111 matching lines @@
   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;
 }
 
+scoped_refptr<display::ManagedDisplayMode> GetDefaultDisplayMode(
+    const display::ManagedDisplayInfo& info) {
+  const auto& modes = info.display_modes();
+  auto iter =
+      std::find_if(modes.begin(), modes.end(),
+                   [](const scoped_refptr<display::ManagedDisplayMode>& mode) {
+                     return mode->is_default();
+                   });
+
+  if (iter == modes.end())
+    return scoped_refptr<display::ManagedDisplayMode>();
+  return *iter;
+}
+
 }  // namespace
 
 using std::string;
 using std::vector;
 
 // static
 int64_t DisplayManager::kUnifiedDisplayId = -10;
 
 DisplayManager::DisplayManager(std::unique_ptr<display::Screen> screen)
     : delegate_(nullptr),
@@ skipping 948 matching lines @@
     if (!IsActiveDisplayId(display_info.id()) ||
         !display::Display::IsInternalDisplayId(display_info.id())) {
       return false;
     }
     mode = GetDisplayModeForNextUIScale(display_info, up);
   }
 
   return mode ? SetDisplayMode(display_id, mode) : false;
 }
 
 bool DisplayManager::SetDisplayUIScale(int64_t id, float ui_scale) {

[oshima, 2016/10/19 21:04:06]

I believe we don't need this other than for tests. Can you move this to test
API?

[afakhry, 2016/10/24 20:21:46]

Done.

   if (!IsActiveDisplayId(id) || !display::Display::IsInternalDisplayId(id)) {
     return false;
   }
   const display::ManagedDisplayInfo& info = GetDisplayInfo(id);
 
   scoped_refptr<display::ManagedDisplayMode> mode =
       GetDisplayModeForUIScale(info, ui_scale);
   if (!mode)
     return false;
   return SetDisplayMode(id, mode);
 }
 
+bool DisplayManager::ResetDisplayToDefaultMode(int64_t display_id) {
+  if (!IsActiveDisplayId(display_id))

[oshima, 2016/10/19 21:04:06]

Check internal display as well.

[afakhry, 2016/10/24 20:21:46]

Done.

+    return false;
+
+  const display::ManagedDisplayInfo& info = GetDisplayInfo(display_id);
+  scoped_refptr<display::ManagedDisplayMode> mode = GetDefaultDisplayMode(info);
+
+  return mode ? SetDisplayMode(display_id, mode) : false;
+}
+
 void DisplayManager::ResetInternalDisplayZoom() {
   if (IsInUnifiedMode()) {
     const display::ManagedDisplayInfo& display_info =
         GetDisplayInfo(DisplayManager::kUnifiedDisplayId);
     const display::ManagedDisplayInfo::ManagedDisplayModeList& modes =
         display_info.display_modes();
     auto iter = std::find_if(
         modes.begin(), modes.end(),
         [](const scoped_refptr<display::ManagedDisplayMode>& mode) {
           return mode->native();
         });
     SetDisplayMode(kUnifiedDisplayId, *iter);
   } else {
-    SetDisplayUIScale(GetDisplayIdForUIScaling(), 1.0f);
+    ResetDisplayToDefaultMode(GetDisplayIdForUIScaling());
   }
 }
 
 void DisplayManager::CreateSoftwareMirroringDisplayInfo(
     DisplayInfoList* display_info_list) {
   // Use the internal display or 1st as the mirror source, then scale
   // the root window so that it matches the external display's
   // resolution. This is necessary in order for scaling to work while
   // mirrored.
   switch (multi_display_mode_) {
@@ skipping 296 matching lines @@
 
 const display::Display& DisplayManager::GetSecondaryDisplay() const {
   CHECK_LE(2U, GetNumDisplays());
   return GetDisplayAt(0).id() ==
                  display::Screen::GetScreen()->GetPrimaryDisplay().id()
              ? GetDisplayAt(1)
              : GetDisplayAt(0);
 }
 
 }  // namespace ash