Take time_offset into account when ticking animations that are Starting

LayerAnimationController::TickAnimations ignores the time_offset for
animations that are Starting and for animations waiting for a synchronized
start time. This CL makes Animation::TrimTimeToCurrentIteration handle
computing the trimmed time for such animations, removing the need for
TickAnimations to have special cases for computing trimmed time.

BUG=284590

Review URL: https://chromiumcodereview.appspot.com/23926003

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@221257 0039d316-1c4b-4281-b951-d872f2087c98

3 files changed, 41 insertions, 10 deletions

diff --git a/cc/animation/animation.cc b/cc/animation/animation.cc
index 214b8bfc..b509cfd 100644
--- a/cc/animation/animation.cc
+++ b/cc/animation/animation.cc
@@ -167,6 +167,12 @@ double Animation::TrimTimeToCurrentIteration(double monotonic_time) const {
   // subtract all time spent paused.
   trimmed -= start_time_ + total_paused_time_;
 
+  // If we're just starting or we're waiting on receiving a start time,
+  // time is 'stuck' at the initial state.
+  if ((run_state_ == Starting && !has_set_start_time()) ||
+      needs_synchronized_start_time())
+    trimmed = time_offset_;
+
   // Zero is always the start of the animation.
   if (trimmed <= 0)
     return 0;
diff --git a/cc/animation/animation_unittest.cc b/cc/animation/animation_unittest.cc
index 337d3ee..23d4169 100644
--- a/cc/animation/animation_unittest.cc
+++ b/cc/animation/animation_unittest.cc
@@ -110,6 +110,41 @@ TEST(AnimationTest, TrimTimeZeroDuration) {
   EXPECT_EQ(0, anim->TrimTimeToCurrentIteration(1.0));
 }
 
+TEST(AnimationTest, TrimTimeStarting) {
+  scoped_ptr<Animation> anim(CreateAnimation(1, 5.0));
+  anim->SetRunState(Animation::Starting, 0.0);
+  EXPECT_EQ(0.0, anim->TrimTimeToCurrentIteration(-1.0));
+  EXPECT_EQ(0.0, anim->TrimTimeToCurrentIteration(0.0));
+  EXPECT_EQ(0.0, anim->TrimTimeToCurrentIteration(1.0));
+  anim->set_time_offset(2.0);
+  EXPECT_EQ(2.0, anim->TrimTimeToCurrentIteration(-1.0));
+  EXPECT_EQ(2.0, anim->TrimTimeToCurrentIteration(0.0));
+  EXPECT_EQ(2.0, anim->TrimTimeToCurrentIteration(1.0));
+  anim->set_start_time(1.0);
+  EXPECT_EQ(0.0, anim->TrimTimeToCurrentIteration(-1.0));
+  EXPECT_EQ(1.0, anim->TrimTimeToCurrentIteration(0.0));
+  EXPECT_EQ(2.0, anim->TrimTimeToCurrentIteration(1.0));
+  EXPECT_EQ(3.0, anim->TrimTimeToCurrentIteration(2.0));
+}
+
+TEST(AnimationTest, TrimTimeNeedsSynchronizedStartTime) {
+  scoped_ptr<Animation> anim(CreateAnimation(1, 5.0));
+  anim->SetRunState(Animation::Running, 0.0);
+  anim->set_needs_synchronized_start_time(true);
+  EXPECT_EQ(0.0, anim->TrimTimeToCurrentIteration(-1.0));
+  EXPECT_EQ(0.0, anim->TrimTimeToCurrentIteration(0.0));
+  EXPECT_EQ(0.0, anim->TrimTimeToCurrentIteration(1.0));
+  anim->set_time_offset(2.0);
+  EXPECT_EQ(2.0, anim->TrimTimeToCurrentIteration(-1.0));
+  EXPECT_EQ(2.0, anim->TrimTimeToCurrentIteration(0.0));
+  EXPECT_EQ(2.0, anim->TrimTimeToCurrentIteration(1.0));
+  anim->set_start_time(1.0);
+  anim->set_needs_synchronized_start_time(false);
+  EXPECT_EQ(1.0, anim->TrimTimeToCurrentIteration(0.0));
+  EXPECT_EQ(2.0, anim->TrimTimeToCurrentIteration(1.0));
+  EXPECT_EQ(3.0, anim->TrimTimeToCurrentIteration(2.0));
+}
+
 TEST(AnimationTest, IsFinishedAtZeroIterations) {
   scoped_ptr<Animation> anim(CreateAnimation(0));
   anim->SetRunState(Animation::Running, 0.0);
diff --git a/cc/animation/layer_animation_controller.cc b/cc/animation/layer_animation_controller.cc
index 08e2db7..04920ac 100644
--- a/cc/animation/layer_animation_controller.cc
+++ b/cc/animation/layer_animation_controller.cc
@@ -671,16 +671,6 @@ void LayerAnimationController::TickAnimations(double monotonic_time) {
       double trimmed =
           active_animations_[i]->TrimTimeToCurrentIteration(monotonic_time);
 
-      // Animation assumes its initial value until it gets the synchronized
-      // start time from the impl thread and can start ticking.
-      if (active_animations_[i]->needs_synchronized_start_time())
-        trimmed = 0;
-
-      // A just-started animation assumes its initial value.
-      if (active_animations_[i]->run_state() == Animation::Starting &&
-          !active_animations_[i]->has_set_start_time())
-        trimmed = 0;
-
       switch (active_animations_[i]->target_property()) {
         case Animation::Transform: {
           const TransformAnimationCurve* transform_animation_curve =