Added frame throttling for window cycling.

Frame throttling starts and ends accordingly when window cycling starts
and ends.
Added test helper and unittests.

Bug: 1107201
Change-Id: I98d9ac1675ca8fd6d2eb7bb178c5c8961166dae4
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2308131
Auto-Submit: Jun Liu <yjliu@chromium.org>
Commit-Queue: Xiyuan Xia <xiyuan@chromium.org>
Reviewed-by: Xiyuan Xia <xiyuan@chromium.org>
Reviewed-by: Jun Mukai <mukai@chromium.org>
Cr-Commit-Position: refs/heads/master@{#790209}

ash/BUILD.gn

@@ -2302,6 +2302,8 @@ static_library("test_support") {
     "drag_drop/drag_drop_controller_test_api.h",
     "fast_ink/laser/laser_pointer_controller_test_api.cc",
     "fast_ink/laser/laser_pointer_controller_test_api.h",
+    "frame_throttler/mock_frame_throttling_observer.cc",
+    "frame_throttler/mock_frame_throttling_observer.h",
     "highlighter/highlighter_controller_test_api.cc",
     "highlighter/highlighter_controller_test_api.h",
     "ime/test_ime_controller_client.cc",

ash/frame_throttler/frame_throttling_controller.cc

@@ -3,6 +3,9 @@
 // found in the LICENSE file.
 
 #include "ash/frame_throttler/frame_throttling_controller.h"
+
+#include <utility>
+
 #include "ash/public/cpp/app_types.h"
 #include "components/viz/common/surfaces/frame_sink_id.h"
 #include "components/viz/host/host_frame_sink_manager.h"
@@ -45,13 +48,16 @@ FrameThrottlingController::~FrameThrottlingController() {
 }
 
 void FrameThrottlingController::StartThrottling(
-    const std::vector<aura::Window*>& windows,
-    uint8_t fps) {
+    const std::vector<aura::Window*>& windows) {
   std::vector<viz::FrameSinkId> frame_sink_ids;
   frame_sink_ids.reserve(windows.size());
 
   CollectBrowserFrameSinkIds(windows, &frame_sink_ids);
-  StartThrottling(frame_sink_ids, fps);
+  StartThrottling(frame_sink_ids, fps_);
+
+  for (auto& observer : observers_) {
+    observer.OnThrottlingStarted(windows);
+  }
 }
 
 void FrameThrottlingController::StartThrottling(
@@ -67,6 +73,18 @@ void FrameThrottlingController::StartThrottling(
 void FrameThrottlingController::EndThrottling() {
   if (context_factory_)
     context_factory_->GetHostFrameSinkManager()->EndThrottling();
+
+  for (auto& observer : observers_) {
+    observer.OnThrottlingEnded();
+  }
+}
+
+void FrameThrottlingController::AddObserver(Observer* observer) {
+  observers_.AddObserver(observer);
+}
+
+void FrameThrottlingController::RemoveObserver(Observer* observer) {
+  observers_.RemoveObserver(observer);
 }
 
 }  // namespace ash

ash/frame_throttler/frame_throttling_controller.h

@@ -7,8 +7,11 @@
 
 #include <stdint.h>
 #include <vector>
+
 #include "ash/ash_export.h"
 #include "base/macros.h"
+#include "base/observer_list.h"
+#include "base/observer_list_types.h"
 #include "components/viz/common/surfaces/frame_sink_id.h"
 
 namespace aura {
@@ -25,23 +28,35 @@ constexpr uint8_t kDefaultThrottleFps = 20;
 
 class ASH_EXPORT FrameThrottlingController {
  public:
+  class Observer : public base::CheckedObserver {
+   public:
+    virtual void OnThrottlingStarted(
+        const std::vector<aura::Window*>& windows) {}
+    virtual void OnThrottlingEnded() {}
+  };
+
   explicit FrameThrottlingController(ui::ContextFactory* context_factory);
+  FrameThrottlingController(const FrameThrottlingController&) = delete;
+  FrameThrottlingController& operator=(const FrameThrottlingController&) =
+      delete;
   ~FrameThrottlingController();
 
   // Starts to throttle the framerate of |windows|.
-  void StartThrottling(const std::vector<aura::Window*>& windows,
-                       uint8_t fps = kDefaultThrottleFps);
+  void StartThrottling(const std::vector<aura::Window*>& windows);
   // Ends throttling of all throttled windows.
   void EndThrottling();
 
+  void AddObserver(Observer* observer);
+  void RemoveObserver(Observer* observer);
+
  private:
   void StartThrottling(const std::vector<viz::FrameSinkId>& frame_sink_ids,
                        uint8_t fps);
 
-  ui::ContextFactory* context_factory_;
-
-  friend class FrameThrottlingControllerTest;
-  DISALLOW_COPY_AND_ASSIGN(FrameThrottlingController);
+  ui::ContextFactory* context_factory_ = nullptr;
+  base::ObserverList<Observer> observers_;
+  // The fps used for throttling.
+  uint8_t fps_ = kDefaultThrottleFps;
 };
 
 }  // namespace ash

ash/frame_throttler/mock_frame_throttling_observer.cc

+// Copyright 2020 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/frame_throttler/mock_frame_throttling_observer.h"
+
+namespace ash {
+
+MockFrameThrottlingObserver::MockFrameThrottlingObserver() = default;
+
+MockFrameThrottlingObserver::~MockFrameThrottlingObserver() = default;
+
+}  // namespace ash

ash/frame_throttler/mock_frame_throttling_observer.h

+// Copyright 2020 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.
+
+#ifndef ASH_FRAME_THROTTLER_MOCK_FRAME_THROTTLING_OBSERVER_H_
+#define ASH_FRAME_THROTTLER_MOCK_FRAME_THROTTLING_OBSERVER_H_
+
+#include <vector>
+
+#include "ash/frame_throttler/frame_throttling_controller.h"
+#include "base/memory/weak_ptr.h"
+#include "testing/gmock/include/gmock/gmock.h"
+
+namespace ash {
+
+class MockFrameThrottlingObserver : public FrameThrottlingController::Observer {
+ public:
+  MockFrameThrottlingObserver();
+  ~MockFrameThrottlingObserver() override;
+
+  MOCK_METHOD(void,
+              OnThrottlingStarted,
+              (const std::vector<aura::Window*>& windows),
+              (override));
+  MOCK_METHOD(void, OnThrottlingEnded, (), (override));
+};
+
+}  // namespace ash
+
+#endif  // ASH_FRAME_THROTTLER_MOCK_FRAME_THROTTLING_OBSERVER_H_

ash/wm/overview/overview_controller_unittest.cc

@@ -7,6 +7,7 @@
 #include <memory>
 
 #include "ash/app_list/test/app_list_test_helper.h"
+#include "ash/frame_throttler/mock_frame_throttling_observer.h"
 #include "ash/keyboard/ui/keyboard_ui_controller.h"
 #include "ash/keyboard/ui/keyboard_util.h"
 #include "ash/keyboard/ui/test/keyboard_test_util.h"
@@ -705,4 +706,28 @@ TEST_F(OverviewVirtualKeyboardTest,
   EXPECT_FALSE(keyboard::IsKeyboardHiding());
 }
 
+// Tests that frame throttling starts and ends accordingly when overview starts
+// and ends.
+TEST_F(OverviewControllerTest, FrameThrottling) {
+  MockFrameThrottlingObserver observer;
+  FrameThrottlingController* frame_throttling_controller =
+      Shell::Get()->frame_throttling_controller();
+  frame_throttling_controller->AddObserver(&observer);
+  const int window_count = 5;
+  std::unique_ptr<aura::Window> created_windows[window_count];
+  std::vector<aura::Window*> windows(window_count, nullptr);
+  for (int i = 0; i < window_count; ++i) {
+    created_windows[i] = CreateTestWindow();
+    windows[i] = created_windows[i].get();
+  }
+
+  auto* controller = Shell::Get()->overview_controller();
+  EXPECT_CALL(observer,
+              OnThrottlingStarted(testing::UnorderedElementsAreArray(windows)));
+  controller->StartOverview();
+  EXPECT_CALL(observer, OnThrottlingEnded());
+  controller->EndOverview();
+  frame_throttling_controller->RemoveObserver(&observer);
+}
+
 }  // namespace ash

ash/wm/window_cycle_controller_unittest.cc

@@ -9,6 +9,7 @@
 
 #include "ash/app_list/test/app_list_test_helper.h"
 #include "ash/focus_cycler.h"
+#include "ash/frame_throttler/mock_frame_throttling_observer.h"
 #include "ash/home_screen/home_screen_controller.h"
 #include "ash/public/cpp/ash_features.h"
 #include "ash/public/cpp/shell_window_ids.h"
@@ -827,4 +828,38 @@ TEST_F(LimitedWindowCycleControllerTest, CycleShowsActiveDeskWindows) {
   EXPECT_EQ(win0.get(), window_util::GetActiveWindow());
 }
 
+// Tests that frame throttling starts and ends accordingly when window cycling
+// starts and ends.
+TEST_F(WindowCycleControllerTest, FrameThrottling) {
+  MockFrameThrottlingObserver observer;
+  FrameThrottlingController* frame_throttling_controller =
+      Shell::Get()->frame_throttling_controller();
+  frame_throttling_controller->AddObserver(&observer);
+  const int window_count = 5;
+  std::unique_ptr<aura::Window> created_windows[window_count];
+  std::vector<aura::Window*> windows(window_count, nullptr);
+  for (int i = 0; i < window_count; ++i) {
+    created_windows[i] = CreateTestWindow();
+    windows[i] = created_windows[i].get();
+  }
+
+  WindowCycleController* controller = Shell::Get()->window_cycle_controller();
+  EXPECT_CALL(observer,
+              OnThrottlingStarted(testing::UnorderedElementsAreArray(windows)));
+  controller->HandleCycleWindow(WindowCycleController::FORWARD);
+  EXPECT_CALL(observer,
+              OnThrottlingStarted(testing::UnorderedElementsAreArray(windows)))
+      .Times(0);
+  controller->HandleCycleWindow(WindowCycleController::FORWARD);
+  EXPECT_CALL(observer, OnThrottlingEnded());
+  controller->CompleteCycling();
+
+  EXPECT_CALL(observer,
+              OnThrottlingStarted(testing::UnorderedElementsAreArray(windows)));
+  controller->HandleCycleWindow(WindowCycleController::FORWARD);
+  EXPECT_CALL(observer, OnThrottlingEnded());
+  controller->CancelCycling();
+  frame_throttling_controller->RemoveObserver(&observer);
+}
+
 }  // namespace ash

ash/wm/window_cycle_list.cc

@@ -10,6 +10,7 @@
 
 #include "ash/accessibility/accessibility_controller_impl.h"
 #include "ash/app_list/app_list_controller_impl.h"
+#include "ash/frame_throttler/frame_throttling_controller.h"
 #include "ash/public/cpp/metrics_util.h"
 #include "ash/public/cpp/shell_window_ids.h"
 #include "ash/public/cpp/window_properties.h"
@@ -477,6 +478,7 @@ WindowCycleList::~WindowCycleList() {
     auto* target_window = windows_[current_index_];
     SelectWindow(target_window);
   }
+  Shell::Get()->frame_throttling_controller()->EndThrottling();
 }
 
 void WindowCycleList::Step(WindowCycleController::Direction direction) {
@@ -621,6 +623,8 @@ void WindowCycleList::InitWindowCycleView() {
   // Close the app list, if it's open in clamshell mode.
   if (!Shell::Get()->tablet_mode_controller()->InTabletMode())
     Shell::Get()->app_list_controller()->DismissAppList();
+
+  Shell::Get()->frame_throttling_controller()->StartThrottling(windows_);
 }
 
 void WindowCycleList::SelectWindow(aura::Window* window) {