Allow Windows to use system Vsync if only one window is swapping

ui/gl/gl_context_egl.cc

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "ui/gl/gl_context_egl.h"
 
 #include "base/debug/trace_event.h"
 #include "base/logging.h"
 #include "base/memory/scoped_ptr.h"
 #include "build/build_config.h"
@@ skipping 165 matching lines @@
   DCHECK(IsCurrent(NULL) && GLSurface::GetCurrent());
 
   // This is a surfaceless context. eglSwapInterval doesn't take any effect in
   // this case and will just return EGL_BAD_SURFACE.
   if (GLSurface::GetCurrent()->IsSurfaceless())
     return;
 
   if (!eglSwapInterval(display_, interval)) {
     LOG(ERROR) << "eglSwapInterval failed with error "
                << GetLastEGLErrorString();
+  } else {
+    GLSurface::GetCurrent()->SetSwapInterval(interval);
   }
 }
 
 std::string GLContextEGL::GetExtensions() {
   const char* extensions = eglQueryString(display_,
                                           EGL_EXTENSIONS);
   if (!extensions)
     return GLContext::GetExtensions();
 
   return GLContext::GetExtensions() + " " + extensions;
 }
 
 bool GLContextEGL::WasAllocatedUsingRobustnessExtension() {
   return GLSurfaceEGL::IsCreateContextRobustnessSupported();
 }
 
 GLContextEGL::~GLContextEGL() {
   Destroy();
 }
 
 #if !defined(OS_ANDROID)
 bool GLContextEGL::GetTotalGpuMemory(size_t* bytes) {
   DCHECK(bytes);
   *bytes = 0;
   return false;
 }
 #endif
 
 }  // namespace gfx