CrOS MD User Row: Media recording indicator.

As per Sebastien's latest specs,
1. Change layout of media indicator icon and label.
2. Show user name for inactive users when media is not recording
3. Fix ripple effect on inactive user row (it should extend to edges of
   menu instead of being inset by 4dp).
4. Switch to vector icon for media indicator. The color matches the tab's
   media indicator (tab_media_recording.icon). The icon itself is
   identical to the tray one, just with different padding, which we can
   ignore since it will be centered in the appropriate amount of space.

BUG=663962

Review-Url: https://codereview.chromium.org/2542493003
Cr-Commit-Position: refs/heads/master@{#435489}

• ash/common/system/user/user_card_view.cc[diff]
• ash/common/system/user/user_card_view.h[diff]
• ash/common/system/user/user_view.cc[diff]