Implement API to have new broadcasts replace existing broadcasts.

Use this in various places where it should serve no purpose to deliver
both broadcasts.  This is intended to reduce somewhat the flurry of
broadcasts that we churn through during boot.

services/java/com/android/server/InputMethodManagerService.java

@@ -949,6 +949,7 @@ public class InputMethodManagerService extends IInputMethodManager.Stub
 
             if (ActivityManagerNative.isSystemReady()) {
                 Intent intent = new Intent(Intent.ACTION_INPUT_METHOD_CHANGED);
+                intent.addFlags(Intent.FLAG_RECEIVER_REPLACE_PENDING);
                 intent.putExtra("input_method_id", id);
                 mContext.sendBroadcast(intent);
             }