[polymer] Merge of master into polymer10-migration

telemetry/telemetry/internal/actions/scroll_bounce.js

Index: telemetry/telemetry/internal/actions/scroll_bounce.js
diff --git a/telemetry/telemetry/internal/actions/scroll_bounce.js b/telemetry/telemetry/internal/actions/scroll_bounce.js
index b41383c096ddd859695f487cd89308371e55134f..ec0fc7ff81f4d88902da0c8525b2de4449160524 100644
--- a/telemetry/telemetry/internal/actions/scroll_bounce.js
+++ b/telemetry/telemetry/internal/actions/scroll_bounce.js
@@ -8,14 +8,16 @@
   function supportedByBrowser() {
     return !!(window.chrome &&
               chrome.gpuBenchmarking &&
-              chrome.gpuBenchmarking.scrollBounce);
+              chrome.gpuBenchmarking.scrollBounce &&
+              chrome.gpuBenchmarking.visualViewportHeight &&
+              chrome.gpuBenchmarking.visualViewportWidth);
   }
 
   function ScrollBounceAction(opt_callback) {
     var self = this;
 
-    this.beginMeasuringHook = function() {}
-    this.endMeasuringHook = function() {}
+    this.beginMeasuringHook = function() {};
+    this.endMeasuringHook = function() {};
 
     this.callback_ = opt_callback;
   }