Update the documentation for ActionMode.Callback2#onGetContentRect
Update the documentation for ActionMode.Callback2#onGetContentRect

Received feedback from a team that it was not clear what the rect
had to include.

Change-Id: I03ca54ee1092e8af3a2078c42104e1ce88490cd1

xorware/android_frameworks_base,xorware/android_frameworks_base,xorware/android_frameworks_base,xorware/android_frameworks_base,xorware/android_frameworks_base,xorware/android_frameworks_base