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/TextDropShadowCache.h b/libs/hwui/TextDropShadowCache.h
index caf089f..1cc10a0 100644
--- a/libs/hwui/TextDropShadowCache.h
+++ b/libs/hwui/TextDropShadowCache.h
@@ -117,7 +117,7 @@
  * Alpha texture used to represent a shadow.
  */
 struct ShadowTexture: public Texture {
-    ShadowTexture(Caches& caches): Texture(caches) {
+    explicit ShadowTexture(Caches& caches): Texture(caches) {
     }
 
     float left;
@@ -127,7 +127,7 @@
 class TextDropShadowCache: public OnEntryRemoved<ShadowText, ShadowTexture*> {
 public:
     TextDropShadowCache();
-    TextDropShadowCache(uint32_t maxByteSize);
+    explicit TextDropShadowCache(uint32_t maxByteSize);
     ~TextDropShadowCache();
 
     /**