Add RasterWindowContext_mac

tools/viewer/sk_app/mac/Window_mac.cpp

 /*
 * Copyright 2016 Google Inc.
 *
 * Use of this source code is governed by a BSD-style license that can be
 * found in the LICENSE file.
 */
 
 #include "SkUtils.h"
 #include "Timer.h"
 #include "WindowContextFactory_mac.h"
@@ skipping 208 matching lines @@
 void Window_mac::show() {
     SDL_ShowWindow(fWindow);
 }
 
 bool Window_mac::attach(BackendType attachType, const DisplayParams& params) {
     this->initWindow(&params);
 
     window_context_factory::MacWindowInfo info;
     info.fWindow = fWindow;
     switch (attachType) {
+        case kRaster_BackendType:
+            fWindowContext = NewRasterForMac(info, params);
+            break;
+            
         case kNativeGL_BackendType:
         default:
             fWindowContext = NewGLForMac(info, params);
             break;
     }
 
     return (SkToBool(fWindowContext));
 }
 
 void Window_mac::onInval() {
     SDL_Event sdlevent;
     sdlevent.type = SDL_WINDOWEVENT;
     sdlevent.window.windowID = fWindowID;
     sdlevent.window.event = SDL_WINDOWEVENT_EXPOSED;
     SDL_PushEvent(&sdlevent);
 }
 
 }   // namespace sk_app