Run the later parts of startup as UI thread tasks

content/browser/browser_startup_configuration.cc

Index: content/browser/browser_startup_configuration.cc
diff --git a/content/renderer/media/video_frame_provider.cc b/content/browser/browser_startup_configuration.cc
similarity index 57%
copy from content/renderer/media/video_frame_provider.cc
copy to content/browser/browser_startup_configuration.cc
index 48f50e06bd2b4595c024366a5120758008fdf65a..2169b444977f3f6eb94e16f24f397ccddd86037f 100644
--- a/content/renderer/media/video_frame_provider.cc
+++ b/content/browser/browser_startup_configuration.cc
@@ -2,12 +2,12 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-#include "content/renderer/media/video_frame_provider.h"
+#include "content/browser/browser_startup_configuration.h"
 
 namespace content {
 
-VideoFrameProvider::VideoFrameProvider() {}
+bool BrowserMayStartAsynchronously() { return false; }
 
-VideoFrameProvider::~VideoFrameProvider() {}
+void BrowserStartupComplete(int result) {}
 
 }  // namespace content