Add a new metric for how many times permissions prompts are shown.

chrome/browser/ui/website_settings/permission_ui_uma_util.cc

+// Copyright 2016 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/ui/website_settings/permission_ui_uma_util.h"
+
+#include "base/metrics/histogram_macros.h"
+#include "chrome/browser/ui/website_settings/permission_bubble_request.h"
+
+void PermissionUiUmaUtil::PermissionPromptShown(
+    const std::vector<PermissionBubbleRequest*>& requests) {
+  PermissionBubbleType permission_prompt_type = PermissionBubbleType::MULTIPLE;
+  if (requests.size() == 1)
+    permission_prompt_type = requests[0]->GetPermissionBubbleType();
+  UMA_HISTOGRAM_ENUMERATION(
+      "Permissions.Prompt.Shown",
+      static_cast<base::HistogramBase::Sample>(permission_prompt_type),
+      static_cast<base::HistogramBase::Sample>(PermissionBubbleType::NUM));
+}