Add new method call back in MountService.

PackageManager invokes this call back when its done handling
the media status update.
Add new uid check for updateExternalMediaStatus
Change killPids method in ActivityManager.
Remove mountsd command in Pm.java We cannot arbitrarily enable/disable
packages in PackageManager now.

Change-Id: I28dcba4afd2b4486f68abdaa1628a31b66544c91

services/java/com/android/server/WindowManagerService.java

@@ -10755,7 +10755,7 @@ public class WindowManagerService extends IWindowManager.Stub
                         pids[i] = pidCandidates.keyAt(i);
                     }
                     try {
-                        if (mActivityManager.killPidsForMemory(pids)) {
+                        if (mActivityManager.killPids(pids, "Free memory")) {
                             killedApps = true;
                         }
                     } catch (RemoteException e) {