Rewrite the cookies pyauto test as browser tests.

content/public/test/browser_test_utils.h

Index: content/public/test/browser_test_utils.h
===================================================================
--- content/public/test/browser_test_utils.h	(revision 153070)
+++ content/public/test/browser_test_utils.h	(working copy)
@@ -42,6 +42,7 @@
 
 namespace content {
 
+class BrowserContext;
 class MessageLoopRunner;
 class RenderViewHost;
 class WebContents;
@@ -100,6 +101,9 @@
     const std::wstring& script,
     std::string* result) WARN_UNUSED_RESULT;
 
+// Returns the cookies for the given url. Runs a nested message loop.
+std::string GetCookies(BrowserContext* browser_context, const GURL& url);
+
 // Watches title changes on a tab, blocking until an expected title is set.
 class TitleWatcher : public NotificationObserver {
  public: