Fix unexpected FrameEvents on BufferQueue reconnect

Helps reduce the number of ALOGE's being hit
when switching between apps.

* Notify Layer when the Producer disconnects.
* Avoid sending event deltas from a previous connection.
* Avoid releasing a frame more than once.

Test: adb shell /data/nativetest/libgui_test/libgui_test
    --gtest_filter=*GetFrameTimestamps*

Change-Id: I64f314be72ddb154b584d726ac382cd468e345bf
diff --git a/include/gui/BufferQueue.h b/include/gui/BufferQueue.h
index a523cd8..c95c535 100644
--- a/include/gui/BufferQueue.h
+++ b/include/gui/BufferQueue.h
@@ -62,11 +62,12 @@
     public:
         explicit ProxyConsumerListener(const wp<ConsumerListener>& consumerListener);
         virtual ~ProxyConsumerListener();
-        virtual void onFrameAvailable(const BufferItem& item) override;
-        virtual void onFrameReplaced(const BufferItem& item) override;
-        virtual void onBuffersReleased() override;
-        virtual void onSidebandStreamChanged() override;
-        virtual void addAndGetFrameTimestamps(
+        void onDisconnect() override;
+        void onFrameAvailable(const BufferItem& item) override;
+        void onFrameReplaced(const BufferItem& item) override;
+        void onBuffersReleased() override;
+        void onSidebandStreamChanged() override;
+        void addAndGetFrameTimestamps(
                 const NewFrameEventsEntry* newTimestamps,
                 FrameEventHistoryDelta* outDelta) override;
     private: