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

chrome/browser/permissions/permission_uma_util.h

 // 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.
 
 #ifndef CHROME_BROWSER_PERMISSIONS_PERMISSION_UMA_UTIL_H_
 #define CHROME_BROWSER_PERMISSIONS_PERMISSION_UMA_UTIL_H_
 
+#include <vector>
+
 #include "base/logging.h"
 #include "base/macros.h"
 
 class GURL;
 class Profile;
 
 namespace content {
 enum class PermissionType;
 }  // namespace content
 
+class PermissionBubbleRequest;
+
 // Enum for UMA purposes, make sure you update histograms.xml if you add new
 // permission actions. Never delete or reorder an entry; only add new entries
 // immediately before PERMISSION_NUM
 enum PermissionAction {
   GRANTED = 0,
   DENIED = 1,
   DISMISSED = 2,
   IGNORED = 3,
   REVOKED = 4,
   REENABLED = 5,
@@ skipping 14 matching lines @@
                                 const GURL& requesting_origin);
   static void PermissionDenied(content::PermissionType permission,
                                const GURL& requesting_origin);
   static void PermissionDismissed(content::PermissionType permission,
                                   const GURL& requesting_origin);
   static void PermissionIgnored(content::PermissionType permission,
                                 const GURL& requesting_origin);
   static void PermissionRevoked(content::PermissionType permission,
                                 const GURL& revoked_origin);
 
+  // UMA specifically for when permission prompts are shown. This should be
+  // roughly equivalent to the metrics above, however it is
+  // useful to have separate UMA to a few reasons:
+  // - to account for, and get data on coalesced permission bubbles
+  // - there are other types of permissions prompts (e.g. download limiting)
+  //   which don't go through PermissionContext
+  // - the above metrics don't always add up (e.g. sum of
+  //   granted+denied+dismissed+ignored is not equal to requested), so it is
+  //   unclear from those metrics alone how many prompts are seen by users.
+  static void PermissionPromptShown(
+      const std::vector<PermissionBubbleRequest*> requests);

[Lei Zhang, 2016/04/19 01:46:05]

Pass by const-ref?

[benwells, 2016/04/20 01:32:10]

Done.

+
  private:
   DISALLOW_IMPLICIT_CONSTRUCTORS(PermissionUmaUtil);
 };
 
 #endif  // CHROME_BROWSER_PERMISSIONS_PERMISSION_UMA_UTIL_H_