device/bluetooth: Add abstract API definition for BluetoothGattCharacteristic.

This CL defines the abstract class BluetoothGattCharacteristic, which represents
remote and local GATT characteristics in the GATT API.

BUG=340525
TEST=Compile Chrome.

Review URL: https://codereview.chromium.org/158283002

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@250340 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 250340
Clears caches of URL and string databases when deleting
Activity Log databases.

BUG=341674

Review URL: https://codereview.chromium.org/143593006

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@250341 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 250341
Change lifetime of image fetchers.

Image fetchers are not deleted when distiller is deleted. Store image fetcher pointers in a ScopedVector instead of a hash_map.

BUG=288015

Review URL: https://codereview.chromium.org/154113006

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@250342 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 250342