AudioPlayer: Update layout to show the volume slider without using popup.
Following the new visual spec, volume-related UI components are updated as follows:
- Volume slider is always shown on the right-bottom corner. It used to be shown as pop-up.
- Clicking volume button toggles mute status, rather than opening volume slider.
- minimum width is expanded to fit time slider and volume slider in a line.
BUG=488229,554448
TEST=manually
Review URL: https://codereview.chromium.org/1491543002
Cr-Commit-Position: refs/heads/master@{#362900}
15 files changed
