Cleanup: Mark some overridden methods with 'SK_OVERRIDE'.

src/gpu/gl/GrGLRenderTarget.h

Index: src/gpu/gl/GrGLRenderTarget.h
diff --git a/src/gpu/gl/GrGLRenderTarget.h b/src/gpu/gl/GrGLRenderTarget.h
index e66475d92ca6bd50c205217aa2491e53dc35a2cc..079e9d5c53a0625b2e84d57523c8661d021413b7 100644
--- a/src/gpu/gl/GrGLRenderTarget.h
+++ b/src/gpu/gl/GrGLRenderTarget.h
@@ -42,9 +42,9 @@ public:
     GrGLuint textureFBOID() const { return fTexFBOID; }
 
     // override of GrRenderTarget
-    virtual GrBackendObject getRenderTargetHandle() const { return this->renderFBOID(); }
-    virtual GrBackendObject getRenderTargetResolvedHandle() const { return this->textureFBOID(); }
-    virtual ResolveType getResolveType() const {
+    virtual GrBackendObject getRenderTargetHandle() const SK_OVERRIDE { return this->renderFBOID(); }
+    virtual GrBackendObject getRenderTargetResolvedHandle() const SK_OVERRIDE { return this->textureFBOID(); }
+    virtual ResolveType getResolveType() const SK_OVERRIDE {
         if (!this->isMultisampled() ||
             fRTFBOID == fTexFBOID) {
             // catches FBO 0 and non MSAA case