Filled in missing dmSize, dmDriverExtra values for EnumDisplaySettings call

These values should be filled in as specified by the MSDN documentation for the function: http://msdn.microsoft.com/en-us/library/windows/desktop/dd162611(v=vs.85).aspx

BUG=418684
TBR=kbr@chromium.org

Review URL: https://codereview.chromium.org/613033002

Cr-Commit-Position: refs/heads/master@{#297320}

ui/gl/gl_surface_win.cc

@@ -118,6 +118,8 @@ class WinVSyncProvider : public VSyncProvider {
     BOOL result = GetMonitorInfo(monitor, &monitor_info);
     if (result) {
       DEVMODE display_info;
+      display_info.dmSize = sizeof(DEVMODE);
+      display_info.dmDriverExtra = 0;
       result = EnumDisplaySettings(monitor_info.szDevice, ENUM_CURRENT_SETTINGS,
           &display_info);
       if (result && display_info.dmDisplayFrequency > 1) {