Add sRGB mode toggle to Viewer.

tools/viewer/sk_app/win/Window_win.cpp

Index: tools/viewer/sk_app/win/Window_win.cpp
diff --git a/tools/viewer/sk_app/win/Window_win.cpp b/tools/viewer/sk_app/win/Window_win.cpp
index 1dd07a6c9c1292fbc8060450647db4dd91455444..9a6f576c04a1eb447add467d5a7ab75d41f8102a 100644
--- a/tools/viewer/sk_app/win/Window_win.cpp
+++ b/tools/viewer/sk_app/win/Window_win.cpp
@@ -264,7 +264,7 @@ void Window_win::show() {
 }
 
 
-bool Window_win::attach(BackEndType attachType, int msaaSampleCount) {
+bool Window_win::attach(BackEndType attachType, int msaaSampleCount, bool srgb) {
     if (kVulkan_BackendType != attachType) {
         return false;
     }
@@ -273,7 +273,7 @@ bool Window_win::attach(BackEndType attachType, int msaaSampleCount) {
     platformData.fHInstance = fHInstance;
     platformData.fHWnd = fHWnd;
 
-    fWindowContext = VulkanWindowContext::Create((void*)&platformData, msaaSampleCount);
+    fWindowContext = VulkanWindowContext::Create((void*)&platformData, msaaSampleCount, srgb);
 
     return (SkToBool(fWindowContext));
 }