Refactor GrGLUniformManager::UniformHandle to initialize itself by default

src/gpu/gl/GrGLUniformHandle.h

Index: src/gpu/gl/GrGLUniformHandle.h
diff --git a/src/gpu/gl/GrGLUniformHandle.h b/src/gpu/gl/GrGLUniformHandle.h
index 231dd31c20eb16b86214d1ca899ff0562fcdb215..77a4ece24d8932dc770ab8823b7b7cd9f1a88520 100644
--- a/src/gpu/gl/GrGLUniformHandle.h
+++ b/src/gpu/gl/GrGLUniformHandle.h
@@ -8,9 +8,8 @@
 #ifndef GrUniformHandle_DEFINED
 #define GrUniformHandle_DEFINED
 
-namespace {
-inline int handle_to_index(GrGLUniformManager::UniformHandle h) { return ~h; }
-inline GrGLUniformManager::UniformHandle index_to_handle(int i) { return ~i; }
+inline GrGLUniformManager::UniformHandle GrGLUniformManager::UniformHandle::CreateFromUniformIndex(int i) {
+    return GrGLUniformManager::UniformHandle(i);
 }
 
 #endif