modules: camera: replace pthread mutex with utils'

Change-Id: Id974e4cc743d27d59634023cfdbba545fbb64e5f
diff --git a/modules/camera/Stream.h b/modules/camera/Stream.h
index b62114e..5efbc52 100644
--- a/modules/camera/Stream.h
+++ b/modules/camera/Stream.h
@@ -20,6 +20,7 @@
 #include <hardware/camera3.h>
 #include <hardware/gralloc.h>
 #include <system/graphics.h>
+#include <utils/Mutex.h>
 
 namespace default_camera_hal {
 // Stream represents a single input or output stream for a camera device.
@@ -49,7 +50,7 @@
         bool mReuse;
 
     private:
-        // Clean up buffer state. must be called with mMutex held.
+        // Clean up buffer state. must be called with mLock held.
         void unregisterBuffers_L();
 
         // The camera device id this stream belongs to
@@ -75,7 +76,7 @@
         // Number of buffers in mBuffers
         unsigned int mNumBuffers;
         // Lock protecting the Stream object for modifications
-        pthread_mutex_t mMutex;
+        android::Mutex mLock;
 };
 } // namespace default_camera_hal