Add GM/slide to simulate Android-style reveal clip

gm/gm.h

 /*
  * Copyright 2011 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #ifndef skiagm_DEFINED
 #define skiagm_DEFINED
 
@@ skipping 82 matching lines @@
         void setCanvasIsDeferred(bool isDeferred) {
             fCanvasIsDeferred = isDeferred;
         }
 
         const SkMatrix& getStarterMatrix() { return fStarterMatrix; }
         void setStarterMatrix(const SkMatrix& matrix) {
             fStarterMatrix = matrix;
         }
 
         bool animate(const SkAnimTimer&);
+        bool handleKey(SkUnichar uni) {
+            return this->onHandleKey(uni);
+        }
 
         virtual void modifyGrContextOptions(GrContextOptions* options) {}
 
         /** draws a standard message that the GM is only intended to be used with the GPU.*/
         static void DrawGpuOnlyMessage(SkCanvas*);
 
     protected:
         virtual void onOnceBeforeDraw() {}
         virtual void onDraw(SkCanvas*) = 0;
         virtual void onDrawBackground(SkCanvas*);
         virtual SkISize onISize() = 0;
         virtual SkString onShortName() = 0;
 
         virtual bool onAnimate(const SkAnimTimer&) { return false; }
+        virtual bool onHandleKey(SkUnichar uni) { return false; }
         virtual SkMatrix onGetInitialTransform() const { return SkMatrix::I(); }
 
     private:
         Mode     fMode;
         SkString fShortName;
         SkColor  fBGColor;
         bool     fCanvasIsDeferred; // work-around problem in srcmode.cpp
         bool     fHaveCalledOnceBeforeDraw;
         SkMatrix fStarterMatrix;
     };
@@ skipping 16 matching lines @@
         SkISize onISize() override;
         SkString onShortName() override;
     private:
         SkString fName;
         void (*fDrawProc)(SkCanvas*);
         SkISize fSize;
     };
 }
 
 #endif