Re-assert vote to disable Aero on switching desktops.

This is required to ensure that the Desktop Window Manager is not
enabled when switching from the logon desktop to the default one.

BUG=129906


Review URL: https://chromiumcodereview.appspot.com/12221104

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@181803 0039d316-1c4b-4281-b951-d872f2087c98

media/video/capture/screen/screen_capturer_win.cc

@@ -306,6 +306,12 @@ void ScreenCapturerWin::PrepareCaptureResources() {
     // If SetThreadDesktop() fails, the thread is still assigned a desktop.
     // So we can continue capture screen bits, just from the wrong desktop.
     desktop_.SetThreadDesktop(input_desktop.Pass());
+
+    // Re-assert our vote to disable Aero.
+    // See crbug.com/124018 and crbug.com/129906.
+    if (composition_func_ != NULL) {
+      (*composition_func_)(DWM_EC_DISABLECOMPOSITION);
+    }
   }
 
   // If the display bounds have changed then recreate GDI resources.