sync: Plumb per-type counter observers to UI

Implements the plumbing to get events from the
DirectoryTypeDebugInfoEmitters in the ModelTypeRegistry, through the
SyncManager, SyncBackendHostCore, and SyncBackendHost to the
ProfileSyncService.

At the moment, there are no observers register and no events
are emitted.  Future patches will include logic to update the
counters and to expose their values on the about:sync page.

BUG=328606

Review URL: https://codereview.chromium.org/269543020

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@268747 0039d316-1c4b-4281-b951-d872f2087c98

1 files changed, 27 insertions, 0 deletions

diff --git a/components/sync_driver/sync_frontend.h b/components/sync_driver/sync_frontend.h
index 47d76be..0a360a8 100644
--- a/components/sync_driver/sync_frontend.h
+++ b/components/sync_driver/sync_frontend.h
@@ -16,6 +16,9 @@ namespace syncer {
 class DataTypeDebugInfoListener;
 class JsBackend;
 class ProtocolEvent;
+struct CommitCounters;
+struct StatusCounters;
+struct UpdateCounters;
 }  // namespace syncer
 
 namespace sync_pb {
@@ -62,6 +65,30 @@ class SyncFrontend {
   // is listening for it.
   virtual void OnProtocolEvent(const syncer::ProtocolEvent& event) = 0;
 
+  // Called when we receive an updated commit counter for a directory type.
+  //
+  // Disabled by default.  Enable by calling
+  // EnableDirectoryTypeDebugInfoForwarding() on the backend.
+  virtual void OnDirectoryTypeCommitCounterUpdated(
+      syncer::ModelType type,
+      const syncer::CommitCounters& counters) = 0;
+
+  // Called when we receive an updated update counter for a directory type.
+  //
+  // Disabled by default.  Enable by calling
+  // EnableDirectoryTypeDebugInfoForwarding() on the backend.
+  virtual void OnDirectoryTypeUpdateCounterUpdated(
+      syncer::ModelType type,
+      const syncer::UpdateCounters& counters) = 0;
+
+  // Called when we receive an updated status counter for a directory type.
+  //
+  // Disabled by default.  Enable by calling
+  // EnableDirectoryTypeDebugInfoForwarding() on the backend.
+  virtual void OnDirectoryTypeStatusCounterUpdated(
+      syncer::ModelType type,
+      const syncer::StatusCounters& counters) = 0;
+
   // The status of the connection to the sync server has changed.
   virtual void OnConnectionStatusChange(
       syncer::ConnectionStatus status) = 0;