Distingush between displayed and remote playback state.
Fixes two of the problems causing bug 593669.
distinguishes between the displayed playback state (which, for example
swiches to paused as soon as the pause button is pressed) and the
remote playback state. Hence avoids side effects when the only the
displayed playback state changes.
Also prevents pause being sent to Chromecast too early.
BUG=
593669
Committed:
https://crrev.com/829655949350c19eea8231f2e2da34679bc42d21
Cr-Commit-Position: refs/heads/master@{#383082}