[Mirror Layers] Added mirrorSurface API to enable mirroring (3/4)

Added a new SurfaceComposer API called mirrorSurface that allows a
client to request a mirror of a particular heirarchy starting from the
passed in layer. The API will return a SurfaceControl that's the parent
of the mirrored layer that can be updated by the client.

Test: MirrorLayerTest
Bug: 131622422
Change-Id: Ia6047f0334eabfc59d6222b2edfd4e9576ba31e5
diff --git a/services/surfaceflinger/Client.h b/services/surfaceflinger/Client.h
index 74e4818..7d7cef8 100644
--- a/services/surfaceflinger/Client.h
+++ b/services/surfaceflinger/Client.h
@@ -62,6 +62,8 @@
                                              LayerMetadata metadata, sp<IBinder>* handle,
                                              sp<IGraphicBufferProducer>* gbp);
 
+    status_t mirrorSurface(const sp<IBinder>& mirrorFromHandle, sp<IBinder>* handle);
+
     virtual status_t clearLayerFrameStats(const sp<IBinder>& handle) const;
 
     virtual status_t getLayerFrameStats(const sp<IBinder>& handle, FrameStats* outStats) const;