[OriginChip, OSX] Delay origin chip hiding for SRP

If the omnibox displays search terms (or any other text) delay hiding
the origin chip until any typing by the user.

The shared code in the model is benign on non-OSX platforms in that it
doesn't lead to any behavioral changes - the chip is already off when
SetInputInProgress is hit.

BUG=349567
R=pkasting@chromium.org

Review URL: https://codereview.chromium.org/198293003

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@257040 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 257040
cc: Add tiling raster tile iterators.

This patch adds PictureLayerTiling::Tiling{Raster,Eviction}TileIterator
classes. This is required for a larger change to tile prioritization.

Currently, the classes are not used by anything except unit and perf
tests.


BUG=329686
R=enne@chromium.org, reveman@chromium.org

Review URL: https://codereview.chromium.org/183663003

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@257041 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 257041