Use URLFetcher to download wallpaper

We previously used XMLHttprequest to download wallpaper, which
required a host permission. Wallpaper API should not require
such host permission (same as img tag doesn't require host
permission). So this CL moves wallpaper download to chrome
and URLFetcher is used to download the wallpaper content.
 

BUG=311607

Review URL: https://codereview.chromium.org/44563002

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@235028 0039d316-1c4b-4281-b951-d872f2087c98
InstantExtended: update tests for Instant Extended (part 2).

Update tests that were using the wrong test for checking the NTP URL. Once
Instant Extended is turned on, IsNTPURL will not return true for
"chrome://newtab", so the tests expecting that particular literal must be
updated. (Ultimately, this should be cleaned up so there is no distinction
between chrome://newtab and chrome-search://local-ntp.. but that will need to
happen later.)

(Note that this is split off from http://crrev.com/24733003.)

BUG=297915

Review URL: https://codereview.chromium.org/58903004

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@235029 0039d316-1c4b-4281-b951-d872f2087c98
[Downloads] Use a WeakPtrFactory in ChromeDownloadManagerDelegate.

ChromeDownloadManagerDelegate is reference counted, and can outlive its
associated Profile/BrowserContext. Since it issues potentially longer
lived tasks, those tasks could complete and issue completion callbacks
after Profile shutdown. Use a WeakPtrFactory to invalidate those
callbacks so that we don't accidentally touch objects that were owned
by the defunct Profile.

In http://crrev.com/69793006 ChromeDownloadManagerDelegate will become
owned by DownloadService and will no longer require being reference
counted.

BUG=317913

Review URL: https://codereview.chromium.org/59903021

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@235030 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 235029
SVN changes up to revision 235030
Add the V8 profiler to the telemetry profilers

Currently support desktop and android.
It allows invoking the V8 profiler similar to the NetLogger profiler.
Output is retrieved but not processed.

Review URL: https://codereview.chromium.org/66033019

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@235031 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 235031