Disable failing telemetry unit tests on chromeos.

tools/telemetry/telemetry/core/backends/chrome_inspector/devtools_client_backend_unittest.py

Index: tools/telemetry/telemetry/core/backends/chrome_inspector/devtools_client_backend_unittest.py
diff --git a/tools/telemetry/telemetry/core/backends/chrome_inspector/devtools_client_backend_unittest.py b/tools/telemetry/telemetry/core/backends/chrome_inspector/devtools_client_backend_unittest.py
index 65f44f7d2320bf8991c8fc7dffeb5b139215c90f..febe4ce66a380bb5f6789ed9ffb93aaf787677a5 100644
--- a/tools/telemetry/telemetry/core/backends/chrome_inspector/devtools_client_backend_unittest.py
+++ b/tools/telemetry/telemetry/core/backends/chrome_inspector/devtools_client_backend_unittest.py
@@ -24,6 +24,7 @@ class DevToolsClientBackendTest(browser_test_case.BrowserTestCase):
     self.assertTrue(self._devtools_client.IsAlive())
 
   @decorators.Enabled('has tabs')
+  @decorators.Disabled('chromeos')  # crbug.com/483212
   def testGetUpdatedInspectableContexts(self):
     self._browser.tabs.New()
     c1 = self._devtools_client.GetUpdatedInspectableContexts()
@@ -58,7 +59,7 @@ class DevToolsClientBackendTest(browser_test_case.BrowserTestCase):
     self.assertEqual(tabs4[0], tabs3[0])
     self.assertEqual(tabs4[1], tabs3[2])
 
-
+  @decorators.Disabled('chromeos')  # crbug.com/483212
   def testGetUpdatedInspectableContextsUpdateContextsData(self):
     c1 = self._devtools_client.GetUpdatedInspectableContexts()
     self.assertEqual(len(c1.contexts), 1)