Add the RenderProcessHost::FastShutdownIfPossible calls to ContentBrowserTest...

Add the RenderProcessHost::FastShutdownIfPossible calls to ContentBrowserTest that I removed in r148507. It looks like this may be preventing the browser from shutting down child processes.
Review URL: https://chromiumcodereview.appspot.com/10833043

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@148686 0039d316-1c4b-4281-b951-d872f2087c98

content/test/content_browser_test.cc

@@ -120,6 +120,11 @@ void ContentBrowserTest::RunTestOnMainThreadLoop() {
   pool.Recycle();
 #endif
 
+  for (RenderProcessHost::iterator i(RenderProcessHost::AllHostsIterator());
+       !i.IsAtEnd(); i.Advance()) {
+    i.GetCurrentValue()->FastShutdownIfPossible();
+  }
+
   Shell::CloseAllWindows();
 }