Change GetAllDisplays() in all screens to return a const vector&.

ui/display/win/screen_win.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 "ui/display/win/screen_win.h"
 
 #include <windows.h>
 #include <shellscalingapi.h>
 
 #include <algorithm>
@@ skipping 366 matching lines @@
 
 gfx::NativeWindow ScreenWin::GetWindowAtScreenPoint(const gfx::Point& point) {
   gfx::Point point_in_pixels = DIPToScreenPoint(point);
   return GetNativeWindowFromHWND(WindowFromPoint(point_in_pixels.ToPOINT()));
 }
 
 int ScreenWin::GetNumDisplays() const {
   return static_cast<int>(screen_win_displays_.size());
 }
 
-std::vector<display::Display> ScreenWin::GetAllDisplays() const {
-  return ScreenWinDisplaysToDisplays(screen_win_displays_);
+const std::vector<display::Display>& ScreenWin::GetAllDisplays() const {
+  return displays_;
 }
 
 display::Display ScreenWin::GetDisplayNearestWindow(
     gfx::NativeView window) const {
   HWND window_hwnd = GetHWNDFromNativeView(window);
   if (!window_hwnd) {
     // When |window| isn't rooted to a display, we should just return the
     // default display so we get some correct display information like the
     // scaling factor.
     return GetPrimaryDisplay();
@@ skipping 37 matching lines @@
 
 gfx::Rect ScreenWin::DIPToScreenRectInWindow(gfx::NativeView view,
                                              const gfx::Rect& dip_rect) const {
   HWND hwnd = view ? GetHWNDFromNativeView(view) : nullptr;
   return DIPToScreenRect(hwnd, dip_rect);
 }
 
 void ScreenWin::UpdateFromDisplayInfos(
     const std::vector<DisplayInfo>& display_infos) {
   screen_win_displays_ = DisplayInfosToScreenWinDisplays(display_infos);
+  displays_ = ScreenWinDisplaysToDisplays(screen_win_displays_);
 }
 
 void ScreenWin::Initialize() {
   singleton_hwnd_observer_.reset(
       new gfx::SingletonHwndObserver(
           base::Bind(&ScreenWin::OnWndProc, base::Unretained(this))));
   UpdateFromDisplayInfos(GetDisplayInfosFromSystem());
   RecordDisplayScaleFactors();
 }
 
@@ skipping 24 matching lines @@
   return ::GetSystemMetrics(metric);
 }
 
 void ScreenWin::OnWndProc(HWND hwnd,
                           UINT message,
                           WPARAM wparam,
                           LPARAM lparam) {
   if (message != WM_DISPLAYCHANGE)
     return;
 
-  std::vector<display::Display> old_displays = GetAllDisplays();
+  std::vector<display::Display> old_displays = std::move(displays_);
   UpdateFromDisplayInfos(GetDisplayInfosFromSystem());
-  change_notifier_.NotifyDisplaysChanged(old_displays, GetAllDisplays());
+  change_notifier_.NotifyDisplaysChanged(old_displays, displays_);
 }
 
 ScreenWinDisplay ScreenWin::GetScreenWinDisplayNearestHWND(HWND hwnd)
     const {
   return GetScreenWinDisplay(MonitorInfoFromWindow(hwnd,
                                                    MONITOR_DEFAULTTONEAREST));
 }
 
 ScreenWinDisplay ScreenWin::GetScreenWinDisplayNearestScreenRect(
     const gfx::Rect& screen_rect) const {
@@ skipping 85 matching lines @@
     if (std::find(unique_scale_factors.begin(), unique_scale_factors.end(),
                   reported_scale) == unique_scale_factors.end()) {
       unique_scale_factors.push_back(reported_scale);
       UMA_HISTOGRAM_SPARSE_SLOWLY("UI.DeviceScale", reported_scale);
     }
   }
 }
 
 }  // namespace win
 }  // namespace display