Add ability to get a screenshot for assist.

New flag you pass in to startSession() to say you want it,
new callback on VoiceInteractionSession to receive it.

Change-Id: I61fdcfdee41a60d46036a2ef16681a9b4181115a
diff --git a/Android.mk b/Android.mk
index 84cad4e..30318d6 100644
--- a/Android.mk
+++ b/Android.mk
@@ -263,6 +263,7 @@
 	core/java/android/speech/tts/ITextToSpeechService.aidl \
 	core/java/com/android/internal/app/IAppOpsCallback.aidl \
 	core/java/com/android/internal/app/IAppOpsService.aidl \
+	core/java/com/android/internal/app/IAssistScreenshotReceiver.aidl \
 	core/java/com/android/internal/app/IBatteryStats.aidl \
 	core/java/com/android/internal/app/IProcessStats.aidl \
 	core/java/com/android/internal/app/IVoiceInteractionManagerService.aidl \