[DevTools] Support broken UMA metric from M49 frontend.

third_party/WebKit/Source/devtools/front_end/devtools.js

Index: third_party/WebKit/Source/devtools/front_end/devtools.js
diff --git a/third_party/WebKit/Source/devtools/front_end/devtools.js b/third_party/WebKit/Source/devtools/front_end/devtools.js
index 8733c4a9492bf474e7ae78a0b08fb083a84232a5..dcbcd758dbdd774c2a3766b16ca9eb30344869a0 100644
--- a/third_party/WebKit/Source/devtools/front_end/devtools.js
+++ b/third_party/WebKit/Source/devtools/front_end/devtools.js
@@ -525,6 +525,9 @@ InspectorFrontendHostImpl.prototype = {
      */
     recordEnumeratedHistogram: function(actionName, actionCode, bucketSize)
     {
+        // Support for M49 frontend.
+        if (actionName === "DevTools.DrawerShown")
+            return;
         DevToolsAPI.sendMessageToEmbedder("recordEnumeratedHistogram", [actionName, actionCode, bucketSize], null);
     },