[Reland][Extensions] Don't count bubble focus loss as acknowledgment

chrome/browser/extensions/proxy_overridden_bubble_delegate.cc

 // Copyright 2014 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "chrome/browser/extensions/proxy_overridden_bubble_delegate.h"
 
 #include "base/metrics/histogram.h"
 #include "base/strings/utf_string_conversions.h"
 #include "chrome/browser/extensions/extension_service.h"
 #include "chrome/browser/extensions/settings_api_helpers.h"
@@ skipping 125 matching lines @@
   UMA_HISTOGRAM_COUNTS_100("ProxyOverriddenBubble.ExtensionCount", count);
 }
 
 void ProxyOverriddenBubbleDelegate::LogAction(
     ExtensionMessageBubbleController::BubbleAction action) {
   UMA_HISTOGRAM_ENUMERATION("ProxyOverriddenBubble.UserSelection",
                             action,
                             ExtensionMessageBubbleController::ACTION_BOUNDARY);
 }
 
+const char* ProxyOverriddenBubbleDelegate::GetKey() {
+  return "ProxyOverriddenBubbleDelegate";
+}
+
 }  // namespace extensions