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

chrome/browser/permissions/permission_uma_util.h

Index: chrome/browser/permissions/permission_uma_util.h
diff --git a/chrome/browser/permissions/permission_uma_util.h b/chrome/browser/permissions/permission_uma_util.h
index 1f5f24b330e0bccd62638ac9557226be2ebc0efb..c4c8001d215749510c9f390aad526442da0db199 100644
--- a/chrome/browser/permissions/permission_uma_util.h
+++ b/chrome/browser/permissions/permission_uma_util.h
@@ -5,6 +5,8 @@
 #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"
 
@@ -15,6 +17,8 @@ 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
@@ -49,6 +53,18 @@ class PermissionUmaUtil {
   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);
+
  private:
   DISALLOW_IMPLICIT_CONSTRUCTORS(PermissionUmaUtil);
 };