Migrate chrome.bluetooth API backend to use device::BluetoothDiscoverySession.

Migrate chrome.bluetooth API backend to use device::BluetoothDiscoverySession.

Modified chrome.bluetooth API code to use the new discovery session API for
device discovery.

This CL is the same as r255262 which was reverted due to a memory leak. The leak
has been addressed in this patch.

BUG=346982, 349942
TEST=1. Run unit_tests and browser_tests with LSan.
     2. Use multiple running extension instances with the bluetooth permission
        and check for the following behavior:
        - Only one session per extension. Calling chrome.bluetooth.stopDiscovery
          from one running app should fail if that app never called
          chrome.bluetooth.startDiscovery.
        - An app's discovery sessions should get cleaned up if that app crashes
          or unloads.
        - Use bt_console and run "power off". This should cause all discovery
          sessions that have been assigned to apps to get marked as inactive.
          Verify by requesting a new discovery session from apps, which should
          succeed.

Committed: https://src.chromium.org/viewvc/chrome?view=rev&revision=255609

[armansito, 2014-03-06 23:52:44]

Leak was in BluetoothEventRouter::DeviceAdded. I forgot to changing from
allocating the bluetooth::Device object on the heap vs in the local scope.

[keybuk, 2014-03-06 23:58:03]

lgtm

[armansito, 2014-03-07 03:10:37]

The CQ bit was checked by armansito@chromium.org

[armansito, 2014-03-07 03:11:09]

On 2014/03/06 23:58:03, keybuk wrote:
> lgtm

linux_asan passed; that's good enough for me. linux_chromeos_asan failed but due
to an unrelated reason.

[commit-bot: I haz the power, 2014-03-07 03:15:56]

CQ is trying da patch. Follow status at
https://chromium-status.appspot.com/cq/armansito@chromium.org/189463002/1

[commit-bot: I haz the power, 2014-03-07 05:40:11]

The CQ bit was unchecked by commit-bot@chromium.org

[commit-bot: I haz the power, 2014-03-07 05:40:12]

Try jobs failed on following builders: linux_chromium_rel

[armansito, 2014-03-07 05:57:42]

The CQ bit was checked by armansito@chromium.org

[commit-bot: I haz the power, 2014-03-07 06:01:30]

CQ is trying da patch. Follow status at
https://chromium-status.appspot.com/cq/armansito@chromium.org/189463002/1

[commit-bot: I haz the power, 2014-03-07 14:17:42]

Change committed as 255609