Disable failing telemetry unit tests on chromeos.

tools/telemetry/telemetry/page/page_run_end_to_end_unittest.py

Index: tools/telemetry/telemetry/page/page_run_end_to_end_unittest.py
diff --git a/tools/telemetry/telemetry/page/page_run_end_to_end_unittest.py b/tools/telemetry/telemetry/page/page_run_end_to_end_unittest.py
index 612b556a7794bcc7db70c93b7ee0e06218702eb9..15b354834ca1484381856f64d6c4a63fd31ced7a 100644
--- a/tools/telemetry/telemetry/page/page_run_end_to_end_unittest.py
+++ b/tools/telemetry/telemetry/page/page_run_end_to_end_unittest.py
@@ -11,11 +11,11 @@ import tempfile
 import unittest
 
 from telemetry import benchmark
+from telemetry import decorators
 from telemetry.core import browser_finder
 from telemetry.core import exceptions
 from telemetry.core import user_agent
 from telemetry.core import util
-from telemetry import decorators
 from telemetry.internal import story_runner
 from telemetry.page import page as page_module
 from telemetry.page import page_set
@@ -275,6 +275,7 @@ class PageRunEndToEndTests(unittest.TestCase):
 
     return did_run[0]
 
+  @decorators.Disabled('chromeos')  # crbug.com/483212
   def testUserAgent(self):
     ps = page_set.PageSet()
     expectations = test_expectations.TestExpectations()