Add SiteEngagementService::GetAllDetails(), to return detailed scores.

chrome/browser/engagement/site_engagement_details.mojom

+// Copyright 2015 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.
+
+module mojom;
+
+import "url/mojo/url.mojom";
+
+struct SiteEngagementDetails {
+  url.mojom.Url origin;
+  double total_score;
+
+  // Details of the components which make up |score|. Note that these may
+  // sum to a value greater than |score| if it exceeds the maximum.
+  double base_score;
+  double installed_bonus;
+  double notifications_bonus;
+};
+
+interface SiteEngagementDetailsProvider {
+  GetSiteEngagementDetails() => (array<SiteEngagementDetails> info);
+  SetSiteEngagementBaseScoreForUrl(url.mojom.Url url, double score);
+};