Add missing includes

Test: compiled
Bug: not applicable
Change-Id: Ie4007970f83e5d08b2d35e78a49d93d696809d7b
diff --git a/services/camera/libcameraservice/device3/Camera3BufferManager.h b/services/camera/libcameraservice/device3/Camera3BufferManager.h
index b5b86a3..f44c4a3 100644
--- a/services/camera/libcameraservice/device3/Camera3BufferManager.h
+++ b/services/camera/libcameraservice/device3/Camera3BufferManager.h
@@ -26,6 +26,8 @@
 
 namespace android {
 
+class IGraphicBufferAlloc;
+
 namespace camera3 {
 
 struct StreamInfo;