Adds UMA for screen rotation animation smoothness.

ash/rotator/screen_rotation_animator.cc

 // Copyright 2015 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/rotator/screen_rotation_animator.h"
 
 #include <string>
 #include <utility>
 #include <vector>
 
 #include "ash/display/window_tree_host_manager.h"
 #include "ash/rotator/screen_rotation_animation.h"
 #include "ash/rotator/screen_rotation_animator_observer.h"
 #include "ash/shell.h"
 #include "base/command_line.h"
+#include "base/lazy_instance.h"

[varkha, 2017/03/24 02:50:25]

Not necessary?

[wutao, 2017/03/24 06:12:38]

Removed.

 #include "base/memory/ptr_util.h"
+#include "base/metrics/histogram_macros.h"
 #include "base/time/time.h"
 #include "ui/aura/window.h"
 #include "ui/compositor/layer.h"
 #include "ui/compositor/layer_animation_observer.h"
 #include "ui/compositor/layer_animation_sequence.h"
 #include "ui/compositor/layer_animator.h"
 #include "ui/compositor/layer_owner.h"
 #include "ui/compositor/layer_tree_owner.h"
 #include "ui/display/display.h"
 #include "ui/display/manager/display_manager.h"
@@ skipping 13 matching lines @@
 // The number of degrees that the rotation animations animate through.
 const int kRotationDegrees = 20;
 
 // The time it takes for the rotation animations to run.
 const int kRotationDurationInMs = 250;
 
 // The rotation factors.
 const int kCounterClockWiseRotationFactor = 1;
 const int kClockWiseRotationFactor = -1;
 
+// The percentage histogram boundary.
+const int kPercentage_MIN = 1;
+const int kPercentage_MAX = 101;
+
 // Aborts the active animations of the layer, and recurses upon its child
 // layers.
 void AbortAnimations(ui::Layer* layer) {
   for (ui::Layer* child_layer : layer->children())
     AbortAnimations(child_layer);
   layer->GetAnimator()->AbortAllAnimations();
 }
 
 display::Display::Rotation GetCurrentScreenRotation(int64_t display_id) {
   return Shell::GetInstance()
@@ skipping 110 matching lines @@
 }  // namespace
 
 struct ScreenRotationAnimator::ScreenRotationRequest {
   ScreenRotationRequest(display::Display::Rotation to_rotation,
                         display::Display::RotationSource from_source)
       : new_rotation(to_rotation), source(from_source) {}
   display::Display::Rotation new_rotation;
   display::Display::RotationSource source;
 };
 
+class ScreenRotationAnimator::ScreenRotationAnimationMetricsReporter
+    : public ui::AnimationMetricsReporter {
+  void Report(int value) override {
+    base::LinearHistogram::FactoryGet(
+        "Ash.Rotator.ScreenRotationAnimationSmoothness", kPercentage_MIN,

[varkha, 2017/03/24 02:50:25]

Suggestion: how about "Ash.Rotation.AnimationSmoothness" to be somewhat similar
to the overview UMA names?

[wutao, 2017/03/24 06:12:38]

Done.

+        kPercentage_MAX, kPercentage_MAX + 1,
+        base::HistogramBase::kUmaTargetedHistogramFlag)
+        ->Add(value);

[varkha, 2017/03/24 02:50:25]

nit: should the line above be indented?

[wutao, 2017/03/24 06:12:38]

git cl format made this.

+  }
+};
+
 ScreenRotationAnimator::ScreenRotationAnimator(int64_t display_id)
     : display_id_(display_id),
       is_rotating_(false),
       disable_animation_timers_for_test_(false),
-      weak_factory_(this) {}
+      weak_factory_(this) {
+  metrics_reporter_ =
+      base::MakeUnique<ScreenRotationAnimationMetricsReporter>();

[varkha, 2017/03/24 02:50:25]

This could be handled in the initializer list.
Also does it have the right lifetime, i.e. could the animation sequence outlive
the ScreenRotationAnimator?

[varkha, 2017/03/24 03:01:33]

One maybe possible scenario to consider is when you shut down the OS shell that
owns |this| while animation is ongoing. You can try making animation duration
long and closing the Chrome OS simulation window.

[wutao, 2017/03/24 06:12:38]

Tried to increase the animation duration and closed the Chrome OS simulation
window. No exception.

[wutao, 2017/03/24 06:12:38]

Moved to initializer list.

Good observation.
|animator| should outlive the animation sequence of |old_layer_tree|.
The animated |old_layer_tree| is a unique_ptr member of |animator|. When
destroying |animator|, |old_layer_tree| is destroyed and the animation sequence
is aborted.
That is possible during destroying |animator|, the |metrics_reporter| is
destroyed first and then animation sequence finished. I will reorder the member
|metrics_reporter_| before |old_layer_tree_owner_|.

[varkha, 2017/03/24 15:08:47]

The lifetime part is subtle. Can you please add a comment about this in the
header or tie the lifetimes tighter in some way. Would be also good to have some
test coverage for this scenario.

+}
 
 ScreenRotationAnimator::~ScreenRotationAnimator() {}
 
 void ScreenRotationAnimator::AnimateRotation(
     std::unique_ptr<ScreenRotationRequest> rotation_request) {
   aura::Window* root_window = GetRootWindow(display_id_);
 
   const gfx::Rect original_screen_bounds = root_window->GetTargetBounds();
 
   const int rotation_factor = GetRotationFactor(
@@ skipping 76 matching lines @@
       ui::LayerAnimator::REPLACE_QUEUED_ANIMATIONS);
   std::unique_ptr<ui::LayerAnimationSequence> animation_sequence =
       base::MakeUnique<ui::LayerAnimationSequence>(std::move(screen_rotation));
   // Add an observer so that the cloned layers can be cleaned up with the
   // animation completes/aborts.
   animation_sequence->AddObserver(old_layer_cleanup_observer.release());
   // In unit test, we can use ash::test::ScreenRotationAnimatorTestApi to
   // control the animation.
   if (disable_animation_timers_for_test_)
     animator->set_disable_timer_for_test(true);
+  animation_sequence->SetAnimationMetricsReporter(metrics_reporter_.get());
   animator->StartAnimation(animation_sequence.release());
 
   rotation_request.reset();
 }
 
 void ScreenRotationAnimator::Rotate(display::Display::Rotation new_rotation,
                                     display::Display::RotationSource source) {
   if (GetCurrentScreenRotation(display_id_) == new_rotation)
     return;
 
@@ skipping 57 matching lines @@
     if (child_layer == old_layer_tree_owner_->root())
       continue;
 
     child_layer->GetAnimator()->StopAnimating();
   }
 
   old_layer_tree_owner_->root()->GetAnimator()->StopAnimating();
 }
 
 }  // namespace ash