Prevent overlay scrollbars expand or hover together

cc/input/single_scrollbar_animation_controller_thinning.cc

Index: cc/input/single_scrollbar_animation_controller_thinning.cc
diff --git a/cc/input/scrollbar_animation_controller_thinning.cc b/cc/input/single_scrollbar_animation_controller_thinning.cc
similarity index 60%
copy from cc/input/scrollbar_animation_controller_thinning.cc
copy to cc/input/single_scrollbar_animation_controller_thinning.cc
index 587c60f79a8b6355b1a23423c0e693ba87ac678e..1ba943e57c4ba8b84380db61b059c8a54c8caa9f 100644
--- a/cc/input/scrollbar_animation_controller_thinning.cc
+++ b/cc/input/single_scrollbar_animation_controller_thinning.cc
@@ -2,7 +2,9 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-#include "cc/input/scrollbar_animation_controller_thinning.h"
+#include "cc/input/single_scrollbar_animation_controller_thinning.h"
+
+#include <algorithm>
 
 #include "base/memory/ptr_util.h"
 #include "base/time/time.h"
@@ -17,30 +19,32 @@ const float kDefaultMouseMoveDistanceToTriggerAnimation = 25.f;
 
 namespace cc {
 
-std::unique_ptr<ScrollbarAnimationControllerThinning>
-ScrollbarAnimationControllerThinning::Create(
+std::unique_ptr<SingleScrollbarAnimationControllerThinning>
+SingleScrollbarAnimationControllerThinning::Create(
     int scroll_layer_id,
+    ScrollbarOrientation orientation,
     ScrollbarAnimationControllerClient* client,
-    base::TimeDelta delay_before_starting,
-    base::TimeDelta resize_delay_before_starting,
+    base::CancelableClosure* delayed_scrollbar_fade,
     base::TimeDelta fade_duration,
     base::TimeDelta thinning_duration) {
-  return base::WrapUnique(new ScrollbarAnimationControllerThinning(
-      scroll_layer_id, client, delay_before_starting,
-      resize_delay_before_starting, fade_duration, thinning_duration));
+  return base::WrapUnique(new SingleScrollbarAnimationControllerThinning(
+      scroll_layer_id, orientation, client, delayed_scrollbar_fade,
+      fade_duration, thinning_duration));
 }
 
-ScrollbarAnimationControllerThinning::ScrollbarAnimationControllerThinning(
-    int scroll_layer_id,
-    ScrollbarAnimationControllerClient* client,
-    base::TimeDelta delay_before_starting,
-    base::TimeDelta resize_delay_before_starting,
-    base::TimeDelta fade_duration,
-    base::TimeDelta thinning_duration)
-    : ScrollbarAnimationController(scroll_layer_id,
-                                   client,
-                                   delay_before_starting,
-                                   resize_delay_before_starting),
+SingleScrollbarAnimationControllerThinning::
+    SingleScrollbarAnimationControllerThinning(
+        int scroll_layer_id,
+        ScrollbarOrientation orientation,
+        ScrollbarAnimationControllerClient* client,
+        base::CancelableClosure* delayed_scrollbar_fade,
+        base::TimeDelta fade_duration,
+        base::TimeDelta thinning_duration)
+    : client_(client),
+      delayed_scrollbar_fade_(delayed_scrollbar_fade),
+      is_animating_(false),
+      scroll_layer_id_(scroll_layer_id),
+      orientation_(orientation),
       opacity_(0.0f),
       captured_(false),
       mouse_is_over_scrollbar_(false),
@@ -55,9 +59,39 @@ ScrollbarAnimationControllerThinning::ScrollbarAnimationControllerThinning(
   ApplyThumbThicknessScale(kIdleThicknessScale);
 }
 
-ScrollbarAnimationControllerThinning::~ScrollbarAnimationControllerThinning() {}
+ScrollbarSet SingleScrollbarAnimationControllerThinning::Scrollbars() const {
+  return client_->ScrollbarsFor(scroll_layer_id_);
+}
+
+bool SingleScrollbarAnimationControllerThinning::Animate(base::TimeTicks now) {
+  if (!is_animating_)
+    return false;
+
+  if (last_awaken_time_.is_null())
+    last_awaken_time_ = now;
+
+  float progress = AnimationProgressAtTime(now);
+  RunAnimationFrame(progress);
+
+  return true;
+}
+
+float SingleScrollbarAnimationControllerThinning::AnimationProgressAtTime(
+    base::TimeTicks now) {
+  base::TimeDelta delta = now - last_awaken_time_;
+  float progress = delta.InSecondsF() / Duration().InSecondsF();
+  return std::max(std::min(progress, 1.f), 0.f);
+}
+
+const base::TimeDelta& SingleScrollbarAnimationControllerThinning::Duration() {
+  if (current_animating_property_ == OPACITY)
+    return fade_duration_;
+  else
+    return thinning_duration_;
+}
 
-void ScrollbarAnimationControllerThinning::RunAnimationFrame(float progress) {
+void SingleScrollbarAnimationControllerThinning::RunAnimationFrame(
+    float progress) {
   if (captured_)
     return;
 
@@ -72,20 +106,40 @@ void ScrollbarAnimationControllerThinning::RunAnimationFrame(float progress) {
     if (current_animating_property_ == THICKNESS) {
       thickness_change_ = NONE;
       SetCurrentAnimatingProperty(OPACITY);
-      if (!mouse_is_near_scrollbar_)
-        PostDelayedAnimationTask(false);
     }
   }
 }
 
-const base::TimeDelta& ScrollbarAnimationControllerThinning::Duration() {
+void SingleScrollbarAnimationControllerThinning::StartAnimation() {
+  delayed_scrollbar_fade_->Cancel();
+  is_animating_ = true;
+  last_awaken_time_ = base::TimeTicks();
+  client_->SetNeedsAnimateForScrollbarAnimation();
+}
+
+void SingleScrollbarAnimationControllerThinning::StopAnimation() {
+  delayed_scrollbar_fade_->Cancel();
+  is_animating_ = false;
+}
+
+void SingleScrollbarAnimationControllerThinning::FadeIn() {
+  if (captured_)
+    return;
+
   if (current_animating_property_ == OPACITY)
-    return fade_duration_;
-  else
-    return thinning_duration_;
+    StopAnimation();
+
+  ApplyOpacity(1.f);
+  ApplyThumbThicknessScale(mouse_is_near_scrollbar_ ? 1.f
+                                                    : kIdleThicknessScale);
+}
+
+bool SingleScrollbarAnimationControllerThinning::ShouldFadeOut() const {
+  return !captured_ && !mouse_is_near_scrollbar_ && !is_animating_ &&
+         current_animating_property_ == OPACITY && !ScrollbarsHidden();
 }
 
-void ScrollbarAnimationControllerThinning::DidMouseDown() {
+void SingleScrollbarAnimationControllerThinning::DidMouseDown() {
   if (!mouse_is_over_scrollbar_ || opacity_ == 0.0f)
     return;
 
@@ -95,7 +149,7 @@ void ScrollbarAnimationControllerThinning::DidMouseDown() {
   ApplyThumbThicknessScale(1.f);
 }
 
-void ScrollbarAnimationControllerThinning::DidMouseUp() {
+void SingleScrollbarAnimationControllerThinning::DidMouseUp() {
   if (!captured_ || opacity_ == 0.0f)
     return;
 
@@ -111,7 +165,7 @@ void ScrollbarAnimationControllerThinning::DidMouseUp() {
   }
 }
 
-void ScrollbarAnimationControllerThinning::DidMouseLeave() {
+void SingleScrollbarAnimationControllerThinning::DidMouseLeave() {
   if (!mouse_is_over_scrollbar_ && !mouse_is_near_scrollbar_)
     return;
 
@@ -126,30 +180,8 @@ void ScrollbarAnimationControllerThinning::DidMouseLeave() {
   StartAnimation();
 }
 
-void ScrollbarAnimationControllerThinning::DidScrollUpdate(bool on_resize) {
-  if (captured_)
-    return;
-
-  ScrollbarAnimationController::DidScrollUpdate(on_resize);
-  ApplyOpacity(1.f);
-  ApplyThumbThicknessScale(mouse_is_near_scrollbar_ ? 1.f
-                                                    : kIdleThicknessScale);
-  SetCurrentAnimatingProperty(OPACITY);
-
-  // Don't fade out the scrollbar when mouse is near.
-  if (mouse_is_near_scrollbar_)
-    StopAnimation();
-}
-
-void ScrollbarAnimationControllerThinning::DidScrollEnd() {
-  ScrollbarAnimationController::DidScrollEnd();
-
-  // Don't fade out the scrollbar when mouse is near.
-  if (mouse_is_near_scrollbar_)
-    StopAnimation();
-}
-
-void ScrollbarAnimationControllerThinning::DidMouseMoveNear(float distance) {
+void SingleScrollbarAnimationControllerThinning::DidMouseMoveNear(
+    float distance) {
   bool mouse_is_over_scrollbar = distance == 0.0f;
   bool mouse_is_near_scrollbar =
       distance < mouse_move_distance_to_trigger_animation_;
@@ -176,11 +208,11 @@ void ScrollbarAnimationControllerThinning::DidMouseMoveNear(float distance) {
   StartAnimation();
 }
 
-bool ScrollbarAnimationControllerThinning::ScrollbarsHidden() const {
+bool SingleScrollbarAnimationControllerThinning::ScrollbarsHidden() const {
   return opacity_ == 0.0f;
 }
 
-float ScrollbarAnimationControllerThinning::ThumbThicknessScaleAt(
+float SingleScrollbarAnimationControllerThinning::ThumbThicknessScaleAt(
     float progress) {
   if (thickness_change_ == NONE)
     return mouse_is_near_scrollbar_ ? 1.f : kIdleThicknessScale;
@@ -188,7 +220,7 @@ float ScrollbarAnimationControllerThinning::ThumbThicknessScaleAt(
   return ((1.f - kIdleThicknessScale) * factor) + kIdleThicknessScale;
 }
 
-float ScrollbarAnimationControllerThinning::AdjustScale(
+float SingleScrollbarAnimationControllerThinning::AdjustScale(
     float new_value,
     float current_value,
     AnimationChange animation_change,
@@ -208,10 +240,13 @@ float ScrollbarAnimationControllerThinning::AdjustScale(
   return result;
 }
 
-void ScrollbarAnimationControllerThinning::ApplyOpacity(float opacity) {
+void SingleScrollbarAnimationControllerThinning::ApplyOpacity(float opacity) {
   for (ScrollbarLayerImplBase* scrollbar : Scrollbars()) {
+    if (scrollbar->orientation() != orientation_)
+      continue;
     if (!scrollbar->is_overlay_scrollbar())
       continue;
+
     float effective_opacity = scrollbar->CanScrollOrientation() ? opacity : 0;
     PropertyTrees* property_trees =
         scrollbar->layer_tree_impl()->property_trees();
@@ -229,28 +264,26 @@ void ScrollbarAnimationControllerThinning::ApplyOpacity(float opacity) {
     }
   }
 
-  bool previouslyVisible = opacity_ > 0.0f;
-  bool currentlyVisible = opacity > 0.0f;
-
   opacity_ = opacity;
-
-  if (previouslyVisible != currentlyVisible)
-    client_->DidChangeScrollbarVisibility();
 }
 
-void ScrollbarAnimationControllerThinning::ApplyThumbThicknessScale(
+void SingleScrollbarAnimationControllerThinning::ApplyThumbThicknessScale(
     float thumb_thickness_scale) {
   for (ScrollbarLayerImplBase* scrollbar : Scrollbars()) {
+    if (scrollbar->orientation() != orientation_)
+      continue;
     if (!scrollbar->is_overlay_scrollbar())
       continue;
 
-    scrollbar->SetThumbThicknessScaleFactor(AdjustScale(
-        thumb_thickness_scale, scrollbar->thumb_thickness_scale_factor(),
-        thickness_change_, kIdleThicknessScale, 1));
+    float scale = AdjustScale(thumb_thickness_scale,
+                              scrollbar->thumb_thickness_scale_factor(),
+                              thickness_change_, kIdleThicknessScale, 1);
+
+    scrollbar->SetThumbThicknessScaleFactor(scale);
   }
 }
 
-void ScrollbarAnimationControllerThinning::SetCurrentAnimatingProperty(
+void SingleScrollbarAnimationControllerThinning::SetCurrentAnimatingProperty(
     AnimatingProperty property) {
   if (current_animating_property_ == property)
     return;