Revert "desks: Enable enhanced desk animations by default."

This reverts commit 3a6b8b82.

Reason for revert: Speculative revert for DesksGestureHandlerTest.HorizontalScrolls and ReverseGestureHandlerTest.SwitchDesk failure on linux-chromeos-dbg
crbug.com/1150701

Original change's description:
> desks: Enable enhanced desk animations by default.
>
> Enabling also exposed a DCHECK where the throughput tracker was being
> Stopped when it was not started. This was previously missed, because
> manual testing was all done on a device, where DCHECKs were disabled.
>
> Bug: 1148923
> Test: none
> Change-Id: I9c9236f04da072e0a63eb118db0969716a71ffdd
> Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2537131
> Commit-Queue: Sammie Quon <sammiequon@chromium.org>
> Reviewed-by: Ahmed Fakhry <afakhry@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#828916}

TBR=afakhry@chromium.org,sammiequon@chromium.org

Change-Id: I2db6cb1342dc0d20d0374d5da96dc9988dbfd5a8
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Bug: 1148923
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2547855Reviewed-by: Keishi Hattori <keishi@chromium.org>
Commit-Queue: Keishi Hattori <keishi@chromium.org>
Cr-Commit-Position: refs/heads/master@{#829090}

ash/public/cpp/ash_features.cc

@@ -45,7 +45,7 @@ const base::Feature kDragToSnapInClamshellMode{
     "DragToSnapInClamshellMode", base::FEATURE_ENABLED_BY_DEFAULT};
 
 const base::Feature kEnhancedDeskAnimations{"EnhancedDeskAnimations",
-                                            base::FEATURE_ENABLED_BY_DEFAULT};
+                                            base::FEATURE_DISABLED_BY_DEFAULT};
 
 const base::Feature kFullRestore{"FullRestore",
                                  base::FEATURE_DISABLED_BY_DEFAULT};

ash/wm/desks/desk_animation_base.cc

@@ -33,10 +33,7 @@ void DeskAnimationBase::Launch() {
   for (auto& observer : controller_->observers_)
     observer.OnDeskSwitchAnimationLaunching();
 
-  // The throughput tracker measures the animation when the user lifts their
-  // fingers off the trackpad, which is done in EndSwipeAnimation.
-  if (!is_continuous_gesture_animation_)
-    throughput_tracker_.Start(GetReportCallback());
+  throughput_tracker_.Start(GetReportCallback());
 
   // This step makes sure that the containers of the target desk are shown at
   // the beginning of the animation (but not actually visible to the user yet,

ash/wm/desks/desk_animation_impl.cc

@@ -83,11 +83,6 @@ bool DeskActivationAnimation::Replace(bool moving_left,
   if (source != switch_source_)
     return false;
 
-  // Do not log any EndSwipeAnimation smoothness metrics if the animation has
-  // been canceled midway by an Replace call.
-  if (is_continuous_gesture_animation_)
-    throughput_tracker_.Cancel();
-
   // If any of the animators are still taking either screenshot, do not replace
   // the animation.
   for (const auto& animator : desk_switch_animators_) {
@@ -140,6 +135,10 @@ bool DeskActivationAnimation::UpdateSwipeAnimation(float scroll_delta_x) {
   if (!is_continuous_gesture_animation_)
     return false;
 
+  // Do not log any EndSwipeAnimation smoothness metrics if the animation has
+  // been canceled midway by an UpdateSwipeAnimation call.
+  throughput_tracker_.Cancel();
+
   presentation_time_recorder_->RequestNext();
 
   // List of animators that need a screenshot. It should be either empty or

ash/wm/gestures/wm_gesture_handler_unittest.cc

@@ -81,8 +81,6 @@ void AddDesk() {
 class WmGestureHandlerTest : public AshTestBase {
  public:
   WmGestureHandlerTest() = default;
-  WmGestureHandlerTest(const WmGestureHandlerTest&) = delete;
-  WmGestureHandlerTest& operator=(const WmGestureHandlerTest&) = delete;
   ~WmGestureHandlerTest() override = default;
 
   void Scroll(float x_offset, float y_offset, int fingers) {
@@ -92,16 +90,11 @@ class WmGestureHandlerTest : public AshTestBase {
   }
 
   void ScrollToSwitchDesks(bool scroll_left) {
-    // Theres no animation when scrolling with enhanced desk animations, so no
-    // need to wait.
-    auto waiter = features::IsEnhancedDeskAnimations()
-                      ? nullptr
-                      : std::make_unique<DeskSwitchAnimationWaiter>();
+    DeskSwitchAnimationWaiter waiter;
     const float x_offset =
         (scroll_left ? -1 : 1) * WmGestureHandler::kHorizontalThresholdDp;
     Scroll(x_offset, 0, kNumFingersForDesksSwitch);
-    if (waiter)
-      waiter->Wait();
+    waiter.Wait();
   }
 
   void MouseWheelScroll(int delta_x, int delta_y, int num_of_times) {
@@ -109,6 +102,9 @@ class WmGestureHandlerTest : public AshTestBase {
     for (int i = 0; i < num_of_times; i++)
       generator->MoveMouseWheel(delta_x, delta_y);
   }
+
+ private:
+  DISALLOW_COPY_AND_ASSIGN(WmGestureHandlerTest);
 };
 
 // Tests a three fingers upwards scroll gesture to enter and a scroll down to
@@ -283,11 +279,6 @@ TEST_F(DesksGestureHandlerTest, NoDeskChanges) {
 
 // Tests that a large scroll only moves to the next desk.
 TEST_F(DesksGestureHandlerTest, NoDoubleDeskChange) {
-  // Enhanced desk animations supports switching multiple desks with large
-  // enough scrolls.
-  if (features::IsEnhancedDeskAnimations())
-    return;
-
   auto* desk_controller = DesksController::Get();
   desk_controller->NewDesk(DesksCreationRemovalSource::kButton);
   desk_controller->NewDesk(DesksCreationRemovalSource::kButton);