[1/2] Base: DownloadManager: add support pause/resume/stop notifications

Add pause, resume and stop functions to make user can pause, resume and stop downloads by manual in downloads application.

Change-Id: I82ffff5a539448faab8933e2b47591199bf24cb9

Conflicts:
	core/java/android/provider/Downloads.java
aapt: i hate if (true) statements

Change-Id: If0d39f4d942067ae2d4ee4d32490b6e079a5f60d
fw: media: Handle NPE due to threading race

Change-Id: I6eab5bc3d687edfa6f0839e439b3314bed4fdcea
Temporarily hide lock screen unlock targets if opening a widget

If the user selects a widget to open, it's very unlikely that they would
want to use any of the slider shortcuts at that moment. Make it easier
to unlock the screen and open the desired widget by temporarily hiding
other targets.

Change-Id: I51d879cc77826e4f7235c5d35b6352e5e83bb7cf