BrowserOptions.extra_browser_args is now a set.

tools/perf/measurements/tab_switching.py

Index: tools/perf/measurements/tab_switching.py
diff --git a/tools/perf/measurements/tab_switching.py b/tools/perf/measurements/tab_switching.py
index b12a1745a5deb225695fbfdfcc298a6a98c03fb3..19eb1de67b98d76e6e88d4febb8eaf7657baff06 100644
--- a/tools/perf/measurements/tab_switching.py
+++ b/tools/perf/measurements/tab_switching.py
@@ -18,9 +18,11 @@ from telemetry.page import page_runner
 
 class TabSwitching(page_measurement.PageMeasurement):
   def CustomizeBrowserOptions(self, options):
-    options.AppendExtraBrowserArg('--enable-stats-collection-bindings')
-    options.AppendExtraBrowserArg('--dom-automation')
-    options.AppendExtraBrowserArg('--reduce-security-for-dom-automation-tests')
+    options.AppendExtraBrowserArgs([
+        '--enable-stats-collection-bindings',
+        '--dom-automation',
+        '--reduce-security-for-dom-automation-tests'
+    ])
 
   def CanRunForPage(self, page):
     return not page.page_set.pages.index(page)