nfc: Add D-Bus client for NFC adapter.

Added D-Bus client code for the NFC Adapter interface.

BUG=304979
TEST=1. chromeos_unittests
     2. On Chrome OS machine, adding and removing a USB NFC adapter should
        cause adapter object proxies to get added and removed. Tapping an NFC
        tag or a Nexus 4 device should log property change events.

Review URL: https://codereview.chromium.org/35873002

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@231189 0039d316-1c4b-4281-b951-d872f2087c98
cc: Allow all types of pending commits to throttle input

SetNeedsCommit is currently the only method that throttles
input events. When SetNeedsUpdate was added to support
abortable commits, it inadvertantly disabled input throttling
for abortabe commits. SetNeesdAnimate has never throttled
input events, but there is not reason to treat it differently.

This patch throttles input for SetNeedsAnimate, SetNeedsUpdate
and SetNeedsCommit now.

BUG=305210

Review URL: https://codereview.chromium.org/37313003

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@231190 0039d316-1c4b-4281-b951-d872f2087c98
Send B/E events to EventCallback for X events

This is a quick fix for DevTools to work. Should investigate if sending
X events to clients via EventCallback is beneficial and feasible and
if yes we should change the API and clients.

BUG=trace-viewer:490
TEST=TraceEventCallbackTest.TraceEventCallback

Review URL: https://codereview.chromium.org/37623002

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@231191 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 231191