Add sRGB mode toggle to Viewer.

tools/viewer/sk_app/Window.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 Window_DEFINED
 #define Window_DEFINED
 
@@ skipping 18 matching lines @@
 
     virtual bool scaleContentToFit() const { return false; }
     virtual bool supportsContentRect() const { return false; }
     virtual SkRect getContentRect() { return SkRect::MakeEmpty(); }
 
     enum BackEndType {
         kNativeGL_BackendType,
         kVulkan_BackendType
     };
 
-    virtual bool attach(BackEndType attachType, int msaaSampleCount) = 0;
+    virtual bool attach(BackEndType attachType, int msaaSampleCount, bool srgb) = 0;
     void detach();
 
     // input handling
     enum Key {
         kNONE_Key,    //corresponds to android's UNKNOWN
 
         kLeftSoftKey_Key,
         kRightSoftKey_Key,
 
         kHome_Key,    //!< the home key - added to match android
@@ skipping 72 matching lines @@
 
     bool onChar(SkUnichar c, uint32_t modifiers);
     bool onKey(Key key, InputState state, uint32_t modifiers);
     bool onMouse(int x, int y, InputState state, uint32_t modifiers);
     void onPaint();
     void onResize(uint32_t width, uint32_t height);
 
     uint32_t width() { return fWidth; }
     uint32_t height() { return fHeight;  }
 
+    bool getSRGB();
+    void setSRGB(bool srgb);
+
 protected:
     Window();
 
     uint32_t     fWidth;
     uint32_t     fHeight;
 
     OnCharFunc   fCharFunc;
     void*        fCharUserData;
     OnKeyFunc    fKeyFunc;
     void*        fKeyUserData;
     OnMouseFunc  fMouseFunc;
     void*        fMouseUserData;
     OnPaintFunc  fPaintFunc;
     void*        fPaintUserData;
 
     WindowContext* fWindowContext;
 };
 
 }   // namespace sk_app
 #endif