CC Animation: Use unordered_map instead of vector.

A performance optimization to align the implementation with
AnimationTimeline::id_to_player_map_

BUG=595584
CQ_INCLUDE_TRYBOTS=tryserver.blink:linux_blink_rel

Review URL: https://codereview.chromium.org/1814103002

Cr-Commit-Position: refs/heads/master@{#382241}

3 files changed, 37 insertions, 41 deletions

diff --git a/cc/animation/animation_host.cc b/cc/animation/animation_host.cc
index 7e6188f..61a24a9 100644
--- a/cc/animation/animation_host.cc
+++ b/cc/animation/animation_host.cc
@@ -167,42 +167,34 @@ AnimationHost::~AnimationHost() {
 }
 
 AnimationTimeline* AnimationHost::GetTimelineById(int timeline_id) const {
-  for (auto& timeline : timelines_)
-    if (timeline->id() == timeline_id)
-      return timeline.get();
-  return nullptr;
+  auto f = id_to_timeline_map_.find(timeline_id);
+  return f == id_to_timeline_map_.end() ? nullptr : f->second.get();
 }
 
 void AnimationHost::ClearTimelines() {
-  EraseTimelines(timelines_.begin(), timelines_.end());
+  for (auto& kv : id_to_timeline_map_)
+    EraseTimeline(kv.second);
+  id_to_timeline_map_.clear();
 }
 
-void AnimationHost::EraseTimelines(AnimationTimelineList::iterator begin,
-                                   AnimationTimelineList::iterator end) {
-  for (auto i = begin; i != end; ++i) {
-    auto& timeline = *i;
-    timeline->ClearPlayers();
-    timeline->SetAnimationHost(nullptr);
-  }
-
-  timelines_.erase(begin, end);
+void AnimationHost::EraseTimeline(scoped_refptr<AnimationTimeline> timeline) {
+  timeline->ClearPlayers();
+  timeline->SetAnimationHost(nullptr);
 }
 
 void AnimationHost::AddAnimationTimeline(
     scoped_refptr<AnimationTimeline> timeline) {
+  DCHECK(timeline->id());
   timeline->SetAnimationHost(this);
-  timelines_.push_back(timeline);
+  id_to_timeline_map_.insert(
+      std::make_pair(timeline->id(), std::move(timeline)));
 }
 
 void AnimationHost::RemoveAnimationTimeline(
     scoped_refptr<AnimationTimeline> timeline) {
-  for (auto iter = timelines_.begin(); iter != timelines_.end(); ++iter) {
-    if (iter->get() != timeline)
-      continue;
-
-    EraseTimelines(iter, iter + 1);
-    break;
-  }
+  DCHECK(timeline->id());
+  EraseTimeline(timeline);
+  id_to_timeline_map_.erase(timeline->id());
 }
 
 void AnimationHost::RegisterLayer(int layer_id, LayerTreeType tree_type) {
@@ -280,7 +272,8 @@ void AnimationHost::PushPropertiesTo(AnimationHost* host_impl) {
 }
 
 void AnimationHost::PushTimelinesToImplThread(AnimationHost* host_impl) const {
-  for (auto& timeline : timelines_) {
+  for (auto& kv : id_to_timeline_map_) {
+    auto& timeline = kv.second;
     AnimationTimeline* timeline_impl =
         host_impl->GetTimelineById(timeline->id());
     if (timeline_impl)
@@ -293,22 +286,25 @@ void AnimationHost::PushTimelinesToImplThread(AnimationHost* host_impl) const {
 
 void AnimationHost::RemoveTimelinesFromImplThread(
     AnimationHost* host_impl) const {
-  AnimationTimelineList& timelines_impl = host_impl->timelines_;
-
-  auto to_erase =
-      std::partition(timelines_impl.begin(), timelines_impl.end(),
-                     [this](AnimationTimelineList::value_type timeline_impl) {
-                       return timeline_impl->is_impl_only() ||
-                              GetTimelineById(timeline_impl->id());
-                     });
-
-  host_impl->EraseTimelines(to_erase, timelines_impl.end());
+  IdToTimelineMap& timelines_impl = host_impl->id_to_timeline_map_;
+
+  // Erase all the impl timelines which |this| doesn't have.
+  for (auto it = timelines_impl.begin(); it != timelines_impl.end();) {
+    auto& timeline_impl = it->second;
+    if (timeline_impl->is_impl_only() || GetTimelineById(timeline_impl->id())) {
+      ++it;
+    } else {
+      host_impl->EraseTimeline(it->second);
+      it = timelines_impl.erase(it);
+    }
+  }
 }
 
 void AnimationHost::PushPropertiesToImplThread(AnimationHost* host_impl) {
   // Firstly, sync all players with impl thread to create ElementAnimations and
   // layer animation controllers.
-  for (auto& timeline : timelines_) {
+  for (auto& kv : id_to_timeline_map_) {
+    AnimationTimeline* timeline = kv.second.get();
     AnimationTimeline* timeline_impl =
         host_impl->GetTimelineById(timeline->id());
     if (timeline_impl)
diff --git a/cc/animation/animation_host.h b/cc/animation/animation_host.h
index 02f37e9..e7f4ae6 100644
--- a/cc/animation/animation_host.h
+++ b/cc/animation/animation_host.h
@@ -6,7 +6,6 @@
 #define CC_ANIMATION_ANIMATION_HOST_H_
 
 #include <unordered_map>
-#include <vector>
 
 #include "base/macros.h"
 #include "base/memory/ref_counted.h"
@@ -34,8 +33,6 @@ class LayerTreeHost;
 
 enum class ThreadInstance { MAIN, IMPL };
 
-typedef std::vector<scoped_refptr<AnimationTimeline>> AnimationTimelineList;
-
 // An AnimationHost contains all the state required to play animations.
 // Specifically, it owns all the AnimationTimelines objects.
 // There is just one AnimationHost for LayerTreeHost on main renderer thread
@@ -161,8 +158,7 @@ class CC_EXPORT AnimationHost {
   void RemoveTimelinesFromImplThread(AnimationHost* host_impl) const;
   void PushPropertiesToImplThread(AnimationHost* host_impl);
 
-  void EraseTimelines(AnimationTimelineList::iterator begin,
-                      AnimationTimelineList::iterator end);
+  void EraseTimeline(scoped_refptr<AnimationTimeline> timeline);
 
   // TODO(loyso): For now AnimationPlayers share LayerAnimationController object
   // if they are attached to the same element(layer). Note that Element can
@@ -171,7 +167,11 @@ class CC_EXPORT AnimationHost {
       std::unordered_map<int, scoped_ptr<ElementAnimations>>;
   LayerToElementAnimationsMap layer_to_element_animations_map_;
 
-  AnimationTimelineList timelines_;
+  // A list of all timelines which this host owns.
+  using IdToTimelineMap =
+      std::unordered_map<int, scoped_refptr<AnimationTimeline>>;
+  IdToTimelineMap id_to_timeline_map_;
+
   scoped_ptr<AnimationRegistrar> animation_registrar_;
   MutatorHostClient* mutator_host_client_;
 
diff --git a/cc/animation/animation_timeline.cc b/cc/animation/animation_timeline.cc
index cb17331..42591d0 100644
--- a/cc/animation/animation_timeline.cc
+++ b/cc/animation/animation_timeline.cc
@@ -38,7 +38,7 @@ void AnimationTimeline::AttachPlayer(scoped_refptr<AnimationPlayer> player) {
   DCHECK(player->id());
   player->SetAnimationHost(animation_host_);
   player->SetAnimationTimeline(this);
-  id_to_player_map_.insert(std::make_pair(player->id(), player));
+  id_to_player_map_.insert(std::make_pair(player->id(), std::move(player)));
 }
 
 void AnimationTimeline::DetachPlayer(scoped_refptr<AnimationPlayer> player) {