net: Reland "Use FileStream asynchronously from UploadFileElementReader"

BUG=294797
TEST=net_unittests

Review URL: https://codereview.chromium.org/142583005

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@246283 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 246283
cc: Remove WorkerPool class and instead use TaskGraphRunner directly.

Removes the unnecessary WorkerPool layer. This makes the job
of the TaskGraphRunner more clear and will allow us to remove
some complexity and unnecessary heap allocations from the
RasterWorkerPool code in follow up patches.

Also moves the kNumRasterTasks switch to content/.

Refactor only, no changes in behavior.

BUG=331844

Review URL: https://codereview.chromium.org/141163019

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@246284 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 246284
Rename InputMethodIBus to InputMethodChromeOS.

There still are references to IBus, but this is a start.

BUG=326780

Review URL: https://codereview.chromium.org/141433005

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@246285 0039d316-1c4b-4281-b951-d872f2087c98
Add UMA statistic to record how many browser action icons there are and how many are visible.

BUG=None
R=yoz@chromium.org

Review URL: https://codereview.chromium.org/141003006

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@246286 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 246286