Fix google-explicit-constructor warnings in gui and ui.

* Add explicit keyword to conversion constructors.
Bug: 28341362
Test: build with WITH_TIDY=1

Change-Id: I476ad1e9a4d47acb11bf4a87ad8baa855f441417
diff --git a/include/gui/Surface.h b/include/gui/Surface.h
index 646203b..592391f 100644
--- a/include/gui/Surface.h
+++ b/include/gui/Surface.h
@@ -66,7 +66,7 @@
      * the controlledByApp flag indicates that this Surface (producer) is
      * controlled by the application. This flag is used at connect time.
      */
-    Surface(const sp<IGraphicBufferProducer>& bufferProducer, bool controlledByApp = false);
+    explicit Surface(const sp<IGraphicBufferProducer>& bufferProducer, bool controlledByApp = false);
 
     /* getIGraphicBufferProducer() returns the IGraphicBufferProducer this
      * Surface was created with. Usually it's an error to use the