sessions: adds tracking interesting session events to prefs

I'm hoping to use this as a debugging aid for folks that encounter
problems. Specifically I'm planning on creating a page that shows
this information, so that if a user thinks restore should have
happened they can open this page for some diagnostic information.

This is just the persistence part.

BUG=1167296
TEST=SessionServiceLogTest*

Change-Id: I0385c45e4b2913bcf7e601a3caf9c8f26ca15546
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2633072
Reviewed-by: David Bienvenu <[email protected]>
Commit-Queue: Scott Violet <[email protected]>
Cr-Commit-Position: refs/heads/master@{#844288}
diff --git a/chrome/browser/prefs/browser_prefs.cc b/chrome/browser/prefs/browser_prefs.cc
index 7a08a794..5d3c84a 100644
--- a/chrome/browser/prefs/browser_prefs.cc
+++ b/chrome/browser/prefs/browser_prefs.cc
@@ -410,6 +410,9 @@
 #include "chrome/browser/media/feeds/media_feeds_service.h"
 #endif
 
+#if BUILDFLAG(ENABLE_SESSION_SERVICE)
+#include "chrome/browser/sessions/session_service_log.h"
+#endif
 namespace {
 
 #if BUILDFLAG(IS_CHROMEOS_ASH)
@@ -908,6 +911,10 @@
   omnibox::RegisterProfilePrefs(registry);
   ZeroSuggestProvider::RegisterProfilePrefs(registry);
 
+#if BUILDFLAG(ENABLE_SESSION_SERVICE)
+  RegisterSessionServiceLogProfilePrefs(registry);
+#endif
+
 #if BUILDFLAG(ENABLE_EXTENSIONS)
   ExtensionWebUI::RegisterProfilePrefs(registry);
   RegisterAnimationPolicyPrefs(registry);