[Telemetry] Fixing credentials login behaviour in case the user is already logged in and using --do…

tools/telemetry/telemetry/browser_backend.py

Index: tools/telemetry/telemetry/browser_backend.py
diff --git a/tools/telemetry/telemetry/browser_backend.py b/tools/telemetry/telemetry/browser_backend.py
index 358cf6358c5dfdd6e6b60d4a34eb779d10a7ad70..57c4f93dd6716119a960447b6c9f23a4c2b1d47d 100644
--- a/tools/telemetry/telemetry/browser_backend.py
+++ b/tools/telemetry/telemetry/browser_backend.py
@@ -7,6 +7,7 @@ import httplib
 import socket
 import json
 import re
+import sys
 import weakref
 
 from telemetry import browser_gone_exception
@@ -146,6 +147,12 @@ class BrowserBackend(object):
     self._webkit_base_revision = 0
     self._tracing_backend = None
 
+    if options.dont_override_profile:
+      sys.stderr.write('Warning: Not overriding profile. This can cause '
+                       'unexpected effects due to profile-specific settings, '
+                       'such as about:flags settings, cookies, and '
+                       'extensions.\n')
+
   def SetBrowser(self, browser):
     self.tabs = TabController(browser, self)