Code cleanup: Replace Element with Document in element.animate()

third_party/WebKit/Source/core/animation/AnimationEffectTiming.cpp

 // Copyright 2014 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 "core/animation/AnimationEffectTiming.h"
 
 #include "bindings/core/v8/ExceptionState.h"
 #include "bindings/core/v8/UnrestrictedDoubleOrString.h"
 #include "core/animation/AnimationEffect.h"
 #include "core/animation/KeyframeEffect.h"
+#include "core/dom/Document.h"
 #include "platform/animation/TimingFunction.h"
 
 namespace blink {
 
 AnimationEffectTiming* AnimationEffectTiming::create(AnimationEffect* parent)
 {
     return new AnimationEffectTiming(parent);
 }
 
 AnimationEffectTiming::AnimationEffectTiming(AnimationEffect* parent)
@@ skipping 98 matching lines @@
     m_parent->updateSpecifiedTiming(timing);
 }
 
 void AnimationEffectTiming::setDirection(String direction)
 {
     Timing timing = m_parent->specifiedTiming();
     TimingInput::setPlaybackDirection(timing, direction);
     m_parent->updateSpecifiedTiming(timing);
 }
 
-void AnimationEffectTiming::setEasing(String easing, ExceptionState& exceptionState)
+void AnimationEffectTiming::setEasing(ExecutionContext* executionContext, String easing, ExceptionState& exceptionState)
 {
     Timing timing = m_parent->specifiedTiming();
-    // The AnimationEffectTiming might not be attached to a document at this
-    // point, so we pass nullptr in to setTimingFunction. This means that these
-    // calls are not considered in the WebAnimationsEasingAsFunction*
-    // UseCounters, but the bug we are tracking there does not come through
-    // this interface.
-    if (TimingInput::setTimingFunction(timing, easing, nullptr, exceptionState))
+    if (TimingInput::setTimingFunction(timing, easing, toDocument(*executionContext), exceptionState))

[suzyh_UTC10 (ex-contributor), 2016/07/07 05:59:44]

Could the toDocument conversion here ever fail, or not make sense for some other
reason? Also, what if the ExecutionContext is null?

My best guess is that this function is currently only called by the
AnimationEffectTiming generated code, and as a result will only be called with a
document as the ExecutionContext. However it's not clear to me that it is
impossible for other code to be written that passes in a different kind of
ExecutionContext.


... And I think your third patchset illustrates my concern. There needs to be
some kind of error checking here and in KeyframeEffect.cpp to prevent crashes
(or give informative/targeted error messages on crashes) in that event.

         m_parent->updateSpecifiedTiming(timing);
 }
 
 DEFINE_TRACE(AnimationEffectTiming)
 {
     visitor->trace(m_parent);
 }
 
 } // namespace blink