Add sRGB mode toggle to Viewer.

tools/viewer/Viewer.h

 /*
 * Copyright 2016 Google Inc.
 *
 * Use of this source code is governed by a BSD-style license that can be
 * found in the LICENSE file.
 */
 
 #ifndef Viewer_DEFINED
 #define Viewer_DEFINED
 
@@ skipping 10 matching lines @@
     Viewer(int argc, char** argv, void* platformData);
     ~Viewer() override;
 
     bool onKey(sk_app::Window::Key key, sk_app::Window::InputState state, uint32_t modifiers);
     bool onChar(SkUnichar, uint32_t modifiers);
     void onPaint(SkCanvas* canvas);
     void onIdle(double ms) override;
 
 private:
     void initSlides();
+    void updateTitle();
     void setupCurrentSlide(int previousSlide);
 
     void drawStats(SkCanvas* canvas);
 
     void changeZoomLevel(float delta);
     void updateMatrix();
 
     sk_app::Window*        fWindow;
 
     static const int kMeasurementCount = 64;  // should be power of 2 for fast mod
@@ skipping 10 matching lines @@
     SkMatrix               fLocalMatrix;
     SkScalar               fZoomCenterX;
     SkScalar               fZoomCenterY;
     SkScalar               fZoomLevel;
     SkScalar               fZoomScale;
 
 };
 
 
 #endif