Increase coverage of telemetry's user_agent_unittest

tools/telemetry/telemetry/core/user_agent_unittest.py

Index: tools/telemetry/telemetry/core/user_agent_unittest.py
diff --git a/tools/telemetry/telemetry/core/user_agent_unittest.py b/tools/telemetry/telemetry/core/user_agent_unittest.py
index 1b50fb24a5eaa10e9e0ec460b6253080da34320f..242ef7657b5f230740a34402d42d2de94e2055a0 100644
--- a/tools/telemetry/telemetry/core/user_agent_unittest.py
+++ b/tools/telemetry/telemetry/core/user_agent_unittest.py
@@ -6,7 +6,16 @@ from telemetry.core import user_agent
 from telemetry.unittest import tab_test_case
 
 
-class UserAgentTest(tab_test_case.TabTestCase):
+class MobileUserAgentTest(tab_test_case.TabTestCase):
+  @classmethod
+  def CustomizeBrowserOptions(cls, options):
+    options.browser_user_agent_type = 'mobile'
+
+  def testUserAgent(self):
+    ua = self._tab.EvaluateJavaScript('window.navigator.userAgent')
+    self.assertEquals(ua, user_agent.UA_TYPE_MAPPING['mobile'])
+
+class TabletUserAgentTest(tab_test_case.TabTestCase):
   @classmethod
   def CustomizeBrowserOptions(cls, options):
     options.browser_user_agent_type = 'tablet'
@@ -14,3 +23,12 @@ class UserAgentTest(tab_test_case.TabTestCase):
   def testUserAgent(self):
     ua = self._tab.EvaluateJavaScript('window.navigator.userAgent')
     self.assertEquals(ua, user_agent.UA_TYPE_MAPPING['tablet'])
+
+class DesktopUserAgentTest(tab_test_case.TabTestCase):
+  @classmethod
+  def CustomizeBrowserOptions(cls, options):
+    options.browser_user_agent_type = 'desktop'
+
+  def testUserAgent(self):
+    ua = self._tab.EvaluateJavaScript('window.navigator.userAgent')
+    self.assertEquals(ua, user_agent.UA_TYPE_MAPPING['desktop'])