Fix/suppress google-explicit-constructor warnings

* Add explicit to conversion constructors/operators

Bug: 28341362
Test: make with WITH_TIDY=1 DEFAULT_GLOBAL_TIDY_CHECKS=-*,google-explicit-constructor
Change-Id: Iac8f3aa14cd04861f6bcbab56b0dfc28c9a89e53
diff --git a/include/input/Input.h b/include/input/Input.h
index cfcafab..756b337 100644
--- a/include/input/Input.h
+++ b/include/input/Input.h
@@ -661,7 +661,7 @@
  */
 class PooledInputEventFactory : public InputEventFactoryInterface {
 public:
-    PooledInputEventFactory(size_t maxPoolSize = 20);
+    explicit PooledInputEventFactory(size_t maxPoolSize = 20);
     virtual ~PooledInputEventFactory();
 
     virtual KeyEvent* createKeyEvent();