Port perf.py's _LoginToGoogleAccount to chrome_remote_control

tools/chrome_remote_control/chrome_remote_control/tab.py

Index: tools/chrome_remote_control/chrome_remote_control/tab.py
diff --git a/tools/chrome_remote_control/chrome_remote_control/tab.py b/tools/chrome_remote_control/chrome_remote_control/tab.py
index 9aa2772d4f9df5e87727f3c15643b452a383b73f..dad551614d807454fa14715a84de771b457b2b63 100644
--- a/tools/chrome_remote_control/chrome_remote_control/tab.py
+++ b/tools/chrome_remote_control/chrome_remote_control/tab.py
@@ -3,6 +3,7 @@
 # found in the LICENSE file.
 from chrome_remote_control import tab_console
 from chrome_remote_control import tab_page
+from chrome_remote_control import tab_credentials
 from chrome_remote_control import tab_runtime
 from chrome_remote_control import util
 
@@ -25,6 +26,7 @@ class Tab(object):
     self._page = tab_page.TabPage(self._inspector_backend)
     self._runtime = tab_runtime.TabRuntime(self._inspector_backend)
     self._console = tab_console.TabConsole(self._inspector_backend)
+    self.credentials = tab_credentials.TabCredentials(self)
 
   def __del__(self):
     self.Close()
@@ -33,6 +35,7 @@ class Tab(object):
     self._console = None
     self._runtime = None
     self._page = None
+    self.credentials = None
     if self._inspector_backend:
       self._inspector_backend.Close()
       self._inspector_backend = None