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/ConsumerBase.h b/include/gui/ConsumerBase.h
index 9307a26..c62e733 100644
--- a/include/gui/ConsumerBase.h
+++ b/include/gui/ConsumerBase.h
@@ -94,7 +94,7 @@
     // buffers from the given IGraphicBufferConsumer.
     // The controlledByApp flag indicates that this consumer is under the application's
     // control.
-    ConsumerBase(const sp<IGraphicBufferConsumer>& consumer, bool controlledByApp = false);
+    explicit ConsumerBase(const sp<IGraphicBufferConsumer>& consumer, bool controlledByApp = false);
 
     // onLastStrongRef gets called by RefBase just before the dtor of the most
     // derived class.  It is used to clean up the buffers so that ConsumerBase