Add sRGB mode toggle to Viewer.

tools/viewer/sk_app/Window.h

Index: tools/viewer/sk_app/Window.h
diff --git a/tools/viewer/sk_app/Window.h b/tools/viewer/sk_app/Window.h
index 3dd558e75ae2362cad4bafe648515311e06d4c1b..56444a67b76639577e9b0e24a7b506c6bce1a54a 100644
--- a/tools/viewer/sk_app/Window.h
+++ b/tools/viewer/sk_app/Window.h
@@ -8,6 +8,7 @@
 #ifndef Window_DEFINED
 #define Window_DEFINED
 
+#include "DisplayParams.h"
 #include "SkTypes.h"
 #include "SkRect.h"
 
@@ -36,7 +37,7 @@ public:
         kVulkan_BackendType
     };
 
-    virtual bool attach(BackEndType attachType, int msaaSampleCount) = 0;
+    virtual bool attach(BackEndType attachType,  const DisplayParams& params) = 0;
     void detach();
 
     // input handling
@@ -129,6 +130,9 @@ public:
     uint32_t width() { return fWidth; }
     uint32_t height() { return fHeight;  }
 
+    const DisplayParams& getDisplayParams();
+    void setDisplayParams(const DisplayParams& params);
+
 protected:
     Window();