Telemetry: IsGestureSourceTypeSupported returns false for touch on Mac.

While 'gestureSourceTypeSupported' has not rolled into stable,
IsGestureSourceTypeSupported returns false for touch input when on Mac.

BUG=372714

Review URL: https://codereview.chromium.org/296113005

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@272328 0039d316-1c4b-4281-b951-d872f2087c98

tools/telemetry/telemetry/page/actions/gesture_action.py

@@ -56,7 +56,8 @@ class GestureAction(page_action.PageAction):
     if tab.EvaluateJavaScript("""
         typeof chrome.gpuBenchmarking.gestureSourceTypeSupported ===
             'undefined'"""):
-      return True
+      return (tab.browser.platform.GetOSName() != 'mac' or
+              gesture_source_type.lower() != 'touch')
 
     return tab.EvaluateJavaScript("""
         chrome.gpuBenchmarking.gestureSourceTypeSupported(