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

chrome/browser/permissions/permission_bubble_request_impl.cc

Index: chrome/browser/permissions/permission_bubble_request_impl.cc
diff --git a/chrome/browser/permissions/permission_bubble_request_impl.cc b/chrome/browser/permissions/permission_bubble_request_impl.cc
index 69feadb8adfadbcb366073d209fa1c11bce6be99..14888966d89a978295aac51bc1567190b5288417 100644
--- a/chrome/browser/permissions/permission_bubble_request_impl.cc
+++ b/chrome/browser/permissions/permission_bubble_request_impl.cc
@@ -161,3 +161,8 @@ void PermissionBubbleRequestImpl::RequestFinished() {
   is_finished_ = true;
   delete_callback_.Run();
 }
+
+PermissionBubbleType PermissionBubbleRequestImpl::GetPermissionBubbleType()
+    const {
+  return PermissionBubbleType::PERMISSION;
+}