Port perf.py's _LoginToGoogleAccount to chrome_remote_control

tools/gpu/page_sets/top_25.json

 {
     "description": "Pages hand-picked for 2012 CrOS scrolling tuning efforts.",
+    "credentials_path": "credentials.json",
     "pages": [
         {
             "url": "https://www.google.com/#hl=en&q=barack+obama",
             "why": "top google property; a google tab is often open"
         },
         {
             "url": "https://mail.google.com/mail/",
             "why": "productivity, top google properties",
             "credentials": "google",
             "is_gmail": true
@@ skipping 115 matching lines @@
         },
         {
             "url": "http://sports.yahoo.com/",
             "why": "#1 Alexa sports"
         },
         {
             "url": "http://techcrunch.com",
             "why": "top tech blog"
         }
     ]
-}
+}