Break dependency between ash::DisplayManager and ash::ScreenAsh

ash/display/screen_ash.cc

 // Copyright 2014 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/screen_ash.h"
 
 #include "ash/aura/wm_window_aura.h"
 #include "ash/common/shelf/shelf_widget.h"
 #include "ash/common/wm/root_window_finder.h"
 #include "ash/display/display_manager.h"
 #include "ash/display/window_tree_host_manager.h"
 #include "ash/root_window_controller.h"
 #include "ash/root_window_settings.h"
 #include "ash/shell.h"
 #include "base/logging.h"
 #include "ui/aura/client/screen_position_client.h"
 #include "ui/aura/env.h"
 #include "ui/aura/window_event_dispatcher.h"
 #include "ui/display/display.h"
 #include "ui/display/display_finder.h"
 #include "ui/display/screen.h"
 
 namespace ash {
 
 namespace {
 
+// We need to keep this in order for unittests to tell if
+// the object in display::Screen::GetScreenByType is for shutdown.
+display::Screen* screen_for_shutdown = nullptr;
+
 DisplayManager* GetDisplayManager() {
   return Shell::GetInstance()->display_manager();
 }
 
 class ScreenForShutdown : public display::Screen {
  public:
-  explicit ScreenForShutdown(ScreenAsh* screen_ash)
+  explicit ScreenForShutdown(display::Screen* screen_ash)
       : display_list_(screen_ash->GetAllDisplays()),
         primary_display_(screen_ash->GetPrimaryDisplay()) {}
 
   // display::Screen overrides:
   gfx::Point GetCursorScreenPoint() override { return gfx::Point(); }
   bool IsWindowUnderCursor(gfx::NativeWindow window) override { return false; }
   gfx::NativeWindow GetWindowAtScreenPoint(const gfx::Point& point) override {
     return NULL;
   }
   int GetNumDisplays() const override { return display_list_.size(); }
@@ skipping 29 matching lines @@
 
   DISALLOW_COPY_AND_ASSIGN(ScreenForShutdown);
 };
 
 }  // namespace
 
 ScreenAsh::ScreenAsh() {}
 
 ScreenAsh::~ScreenAsh() {}
 
-void ScreenAsh::NotifyMetricsChanged(const display::Display& display,
-                                     uint32_t metrics) {
-  FOR_EACH_OBSERVER(display::DisplayObserver, observers_,
-                    OnDisplayMetricsChanged(display, metrics));
-}
-
-void ScreenAsh::NotifyDisplayAdded(const display::Display& display) {
-  FOR_EACH_OBSERVER(display::DisplayObserver, observers_,
-                    OnDisplayAdded(display));
-}
-
-void ScreenAsh::NotifyDisplayRemoved(const display::Display& display) {
-  FOR_EACH_OBSERVER(display::DisplayObserver, observers_,
-                    OnDisplayRemoved(display));
-}
-
 gfx::Point ScreenAsh::GetCursorScreenPoint() {
   return aura::Env::GetInstance()->last_mouse_location();
 }
 
 bool ScreenAsh::IsWindowUnderCursor(gfx::NativeWindow window) {
   return GetWindowAtScreenPoint(
              display::Screen::GetScreen()->GetCursorScreenPoint()) == window;
 }
 
 gfx::NativeWindow ScreenAsh::GetWindowAtScreenPoint(const gfx::Point& point) {
@@ skipping 64 matching lines @@
   // Fallback to the primary display if there is no matching display.
   return matching ? *matching : GetPrimaryDisplay();
 }
 
 display::Display ScreenAsh::GetPrimaryDisplay() const {
   return GetDisplayManager()->GetDisplayForId(
       WindowTreeHostManager::GetPrimaryDisplayId());
 }
 
 void ScreenAsh::AddObserver(display::DisplayObserver* observer) {
-  observers_.AddObserver(observer);
+  GetDisplayManager()->AddObserver(observer);
 }
 
 void ScreenAsh::RemoveObserver(display::DisplayObserver* observer) {
-  observers_.RemoveObserver(observer);
+  GetDisplayManager()->RemoveObserver(observer);
 }
 
-display::Screen* ScreenAsh::CloneForShutdown() {
-  return new ScreenForShutdown(this);
+// static
+DisplayManager* ScreenAsh::CreateDisplayManager() {
+  std::unique_ptr<ScreenAsh> screen(new ScreenAsh);
+
+  display::Screen* current = display::Screen::GetScreen();
+  // If there is no native, or the native was for shutdown,
+  // use ash's screen.
+  if (!current || current == screen_for_shutdown)
+    display::Screen::SetScreenInstance(screen.get());
+  return new DisplayManager(std::move(screen));
+}
+
+// static
+void ScreenAsh::CreateScreenForShutdown() {
+  delete screen_for_shutdown;
+  // fix this up...
+  screen_for_shutdown = new ScreenForShutdown(display::Screen::GetScreen());
+  display::Screen::SetScreenInstance(screen_for_shutdown);
 }
 
 }  // namespace ash