Hoist active document check from UpdateAnimationsAndScheduleFrameIfNeeded

We should aim to have these checks around the API "border" and then
prevent certain actions when it is true (like scheduling frames). This
hoists the check in UpdateAnimationsAndScheduleFrameIfNeeded(...) out
into its callers adds TODOs where it seems we shouldn't need to check
(per the previous sentence).

Bug: 998526
Change-Id: I782a41033c33dba38b4923e96e84531858675c0c
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1827422Reviewed-by: Stephen Chenney <schenney@chromium.org>
Commit-Queue: Fredrik Söderquist <fs@opera.com>
Cr-Commit-Position: refs/heads/master@{#700391}

third_party/blink/renderer/core/svg/animation/smil_time_container.cc

@@ -258,7 +258,10 @@ void SMILTimeContainer::Unpause() {
 void SMILTimeContainer::SetElapsed(SMILTime elapsed) {
   presentation_time_ = elapsed;
 
-  // If the document hasn't finished loading, |m_presentationTime| will be
+  if (!GetDocument().IsActive())
+    return;
+
+  // If the document hasn't finished loading, |presentation_time_| will be
   // used as the start time to seek to once it's possible.
   if (!IsStarted())
     return;
@@ -285,6 +288,7 @@ void SMILTimeContainer::SetElapsed(SMILTime elapsed) {
 void SMILTimeContainer::ScheduleAnimationFrame(base::TimeDelta delay_time) {
   DCHECK(IsTimelineRunning());
   DCHECK(!wakeup_timer_.IsActive());
+  DCHECK(GetDocument().IsActive());
 
   const base::TimeDelta kLocalMinimumDelay =
       base::TimeDelta::FromSecondsD(DocumentTimeline::kMinimumDelay);
@@ -312,12 +316,17 @@ void SMILTimeContainer::ScheduleWakeUp(
 void SMILTimeContainer::WakeupTimerFired(TimerBase*) {
   DCHECK(frame_scheduling_state_ == kSynchronizeAnimations ||
          frame_scheduling_state_ == kFutureAnimationFrame);
-  if (frame_scheduling_state_ == kFutureAnimationFrame) {
+  FrameSchedulingState previous_frame_scheduling_state =
+      frame_scheduling_state_;
+  frame_scheduling_state_ = kIdle;
+  // TODO(fs): The timeline should not be running if we're in an inactive
+  // document, so this should be turned into a DCHECK.
+  if (!GetDocument().IsActive())
+    return;
+  if (previous_frame_scheduling_state == kFutureAnimationFrame) {
     DCHECK(IsTimelineRunning());
-    frame_scheduling_state_ = kIdle;
     ServiceOnNextFrame();
   } else {
-    frame_scheduling_state_ = kIdle;
     UpdateAnimationsAndScheduleFrameIfNeeded(Elapsed());
   }
 }
@@ -402,8 +411,11 @@ void SMILTimeContainer::ServiceOnNextFrame() {
 void SMILTimeContainer::ServiceAnimations() {
   if (frame_scheduling_state_ != kAnimationFrame)
     return;
-
   frame_scheduling_state_ = kIdle;
+  // TODO(fs): The timeline should not be running if we're in an inactive
+  // document, so this should be turned into a DCHECK.
+  if (!GetDocument().IsActive())
+    return;
   UpdateAnimationsAndScheduleFrameIfNeeded(Elapsed());
 }
 
@@ -419,8 +431,7 @@ bool SMILTimeContainer::CanScheduleFrame(SMILTime earliest_fire_time) const {
 
 void SMILTimeContainer::UpdateAnimationsAndScheduleFrameIfNeeded(
     SMILTime elapsed) {
-  if (!GetDocument().IsActive())
-    return;
+  DCHECK(GetDocument().IsActive());
 
   UpdateAnimationTimings(elapsed);
   ApplyAnimationValues(elapsed);