Fix google-explicit-constructor warnings in frameworks/base

* Add explicit keyword to conversion constructors.
* Add NOLINT to implicit conversion constructors.

Bug: 28341362
Test: build with clang-tidy
Change-Id: Ie4d37072ab57d1662d18db4de1c8577247f43337
diff --git a/libs/hwui/AnimationContext.h b/libs/hwui/AnimationContext.h
index 909ed36..395dc73 100644
--- a/libs/hwui/AnimationContext.h
+++ b/libs/hwui/AnimationContext.h
@@ -57,7 +57,7 @@
 
 private:
     friend class AnimationContext;
-    AnimationHandle(AnimationContext& context);
+    explicit AnimationHandle(AnimationContext& context);
     AnimationHandle(RenderNode& animatingNode, AnimationContext& context);
     ~AnimationHandle();
 
@@ -75,7 +75,7 @@
 class AnimationContext {
     PREVENT_COPY_AND_ASSIGN(AnimationContext);
 public:
-    ANDROID_API AnimationContext(renderthread::TimeLord& clock);
+    ANDROID_API explicit AnimationContext(renderthread::TimeLord& clock);
     ANDROID_API virtual ~AnimationContext();
 
     nsecs_t frameTimeMs() { return mFrameTimeMs; }