Rename VulkanViewer to Viewer, take 2.

tools/viewer/Window.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 "Window.h"
 
 #include "SkSurface.h"
 #include "SkCanvas.h"
 #include "VulkanTestContext.h"
 
+namespace sk_app {
+
 static bool default_char_func(SkUnichar c, uint32_t modifiers, void* userData) {
     return false;
 }
 
 static bool default_key_func(Window::Key key, Window::InputState state, uint32_t modifiers, 
                              void* userData) {
     return false;
 }
 
 static bool default_mouse_func(int x, int y, Window::InputState state, uint32_t modifiers, 
@@ skipping 41 matching lines @@
         // try recreating testcontext
     }
 
 }
 
 void Window::onResize(uint32_t w, uint32_t h) {
     fWidth = w;
     fHeight = h;
     fTestContext->resize(w, h);
 }
+
+}   // namespace sk_app