Implement a basic Site Engagement Score service.

The Site Engagement Service will be used to perform resource allocation
(such as battery or disk) based on how much users interact with the
origin in question.

BUG=464234

Review URL: https://codereview.chromium.org/1077063002

Cr-Commit-Position: refs/heads/master@{#326431}
diff --git a/chrome/browser/BUILD.gn b/chrome/browser/BUILD.gn
index e3fb61b5..c6925c3 100644
--- a/chrome/browser/BUILD.gn
+++ b/chrome/browser/BUILD.gn
@@ -185,6 +185,9 @@
     sources += rebase_path(gypi_values.chrome_browser_content_settings_sources,
                            ".",
                            "//chrome")
+    sources += rebase_path(gypi_values.chrome_browser_engagement_sources,
+                           ".",
+                           "//chrome")
     sources +=
         rebase_path(gypi_values.chrome_browser_favicon_sources, ".", "//chrome")
     sources +=