undo shrikant changes to ash shelf

The autohide option of the ash tray/taskbar is back, by popular demand.
More info on the bug.

TBR=shrikant
BUG=292864

Review URL: https://codereview.chromium.org/152143007

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@249586 0039d316-1c4b-4281-b951-d872f2087c98
Part 2 of search provider refactoring.

Moves field_trial_triggered_ and field_trial_triggered_in_session_
fields to base_search_provider. Moves shared AddProviderInfo and
field_trial_triggered_in_session methods using those fields into the
superclass.

BUG=338955
TBR=mpearson@chromium.org

Review URL: https://codereview.chromium.org/143263019

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@249587 0039d316-1c4b-4281-b951-d872f2087c98
Fixes the search key asset.

BUG=339552

Review URL: https://codereview.chromium.org/142703013

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@249588 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 249588
cc: Switch to vector based TaskGraph implementation.

Provides improved performance for graph sizes used with impl-side
painting. Here are two reasons for why this is better:

1. TaskGraph creation can be done without any heap allocations.
Prior to this we spent most of the graph construction time
creating and deleting objects. This eliminates that completely.

2. Linear scans are typically faster than hash map lookups for the
number of nodes and edges used in our task graphs. A large graph
with raster tasks typically has ~50 nodes and ~100 edges.

Improvement in graph construction performance is somewhere between
5x-10x on desktop and likely even greater on Android where heap
allocations might be more expensive. Graph scheduling performance
is up by 3x-10x while the improvement to execution time is a more
moderate 2x-5x. Execution cost is less important as it's paid by
worker threads and already considered good enough before this
change.

There's still room for improvement after this change. ie. by
keeping graph edges sorted, DependentIterator performance can be
 improved.

Trivial changes to our RasterWorkerPool implementations are needed
to further avoid heap allocations and fully take advantage of the
performance improvements in this patch. This has been left as follow
up work.

BUG=246546

Review URL: https://codereview.chromium.org/154003006

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@249589 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 249589