AwContents#computeScroll uses the AnimationUtils.getCurrentFrameTimeMillis() as the animation timestamp, which is read from SystemClock. This is different from the frame time in Choreographer. As a result, this has caused tiny 'sleeps' during fling animation.

This is a problem for L+. Android will fix AnimationUtils.getCurrentFrameTimeMillis to be backed by Choreographer.
But in order for Android WebView to work properly on L+, we need to stop using AnimationUtils.getCurrentFrameTimeMillis and instead read from Choreographer's frame time directly.

See internal bug b/30674719 for more details.