Send three spaced repeat query when the user opens the devices page

Send three queries to the network when the user opens chrome://devices/,
one zero seconds after the user opens the page, one 1 second, and one 2
seconds after.

BUG=303428
TEST=Manual with wireshark

Review URL: https://codereview.chromium.org/25585004

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@226723 0039d316-1c4b-4281-b951-d872f2087c98
Abstract content::BrowserThread usage out of AutofillWebDataBackendImpl.

Instead, this class now takes in MessageLoopProxy's for the UI thread and DB
thread. All operations that were previously on BrowserThread are changed to the
corresponding operations on MessageLoopProxy.

A follow-up change will perform a similar abstraction for AutofillWebDataService.

BUG=303017

Review URL: https://codereview.chromium.org/25783002

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@226724 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 226724
Implement short term caching for People search.
Currently during a people search session, if a person presses backspace or types in the same query again, we run another web query. Change this by reusing the webstore short term caching code.

This is a pre-requisite for the larger work for implementing cross-session caching for people search.

R=xiyuan@chromium.org
BUG=295163

Review URL: https://codereview.chromium.org/25550004

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@226725 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 226725
Fix some typos in Files.app code.

BUG=none

Review URL: https://codereview.chromium.org/25835002

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@226726 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 226726
Files.app: Delay disappearing a completed progress item.

Originally a progress item disappears immediately after it is completed.
This CL adds the timeout callback to delay the disappearing.

BUG=277432
TEST=manually

Review URL: https://codereview.chromium.org/25709003

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@226727 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 226727
Don't override optional audio constraints with defaults.

The app should be able to set media constraints in either the mandatory
or optional fields and have them respected.

TESTED=Using apprtc with this change to allow passing constraints:
http://review.webrtc.org/2345004/
verified that constraints in both mandatory and optional fields are
not overridden by defaults.

Review URL: https://codereview.chromium.org/25683007

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@226728 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 226728