Appears mozrunner has changed; need to update which module to import.

This surprised me quite a bit, but I don't think there's anything
wrong with my checkout that would explain why I have to do this.
I guess mozrunner has changed while the test was broken...

Bug:751211
Change-Id: I7ed0aa6a904e697de010014aa1ea2e2116e14909
Reviewed-on: https://webrtc-review.googlesource.com/3401
Reviewed-by: Edward Lemur <ehmaldonado@webrtc.org>
diff --git a/run_firefox_webrtc.py b/run_firefox_webrtc.py
index 91e71c3..13c7445 100755
--- a/run_firefox_webrtc.py
+++ b/run_firefox_webrtc.py
@@ -21,7 +21,7 @@
 sys.path.append(os.path.join(THIRD_PARTY_DIR, 'mozrunner'))
 
 from mozprofile import profile
-from mozrunner import runner
+import mozrunner
 
 WEBRTC_PREFERENCES = {
     # Automatically gives permission to access the camera/microphone and
@@ -43,9 +43,9 @@
     parser.error('You must specify the web page to browse to.')
 
   firefox_profile = profile.FirefoxProfile(preferences=WEBRTC_PREFERENCES)
-  firefox_runner = runner.FirefoxRunner(profile=firefox_profile,
-                                        binary=options.binary,
-                                        cmdargs=[options.webpage])
+  firefox_runner = mozrunner.FirefoxRunner(profile=firefox_profile,
+                                           binary=options.binary,
+                                           cmdargs=[options.webpage])
   def KillFirefox(signum, frame):
     firefox_runner.stop()
   signal.signal(signal.SIGTERM, KillFirefox)