Persist Directory to disk when the app is backgrounded.

chrome/browser/sync/glue/sync_backend_host_core.cc

Index: chrome/browser/sync/glue/sync_backend_host_core.cc
diff --git a/chrome/browser/sync/glue/sync_backend_host_core.cc b/chrome/browser/sync/glue/sync_backend_host_core.cc
index 2a78040131e0e7894375a1f11fa40c2e0285eb66..ff5a09962f2c987061b5e67e72e4bc0fd71eb893 100644
--- a/chrome/browser/sync/glue/sync_backend_host_core.cc
+++ b/chrome/browser/sync/glue/sync_backend_host_core.cc
@@ -23,6 +23,7 @@
 #include "sync/internal_api/public/sync_context_proxy.h"
 #include "sync/internal_api/public/sync_manager.h"
 #include "sync/internal_api/public/sync_manager_factory.h"
+#include "sync/syncable/directory.h"
 #include "url/gurl.h"
 
 // Helper macros to log with the syncer thread name; useful when there
@@ -662,6 +663,15 @@ void SyncBackendHostCore::DoRetryConfiguration(
              retry_callback);
 }
 
+void SyncBackendHostCore::DoFlushDirectory() {

[pval...(no longer on Chromium), 2014/09/23 20:11:12]

Max/Nicolas: Here is an idea for testing this forced-flush feature:

1) Add a callback param that populates a value in ProfileSyncServiceAndroid
(let's call it wasFlushDirectorySuccessful) and call it with the return value of
directory->SaveChanges().

2) Add a JNI method to ProfileSyncServiceAndroid that returns
wasFlushDirectorySuccessful.

3) In a Java test, we can trigger the PAUSED state change (see
https://code.google.com/p/chromium/codesearch#chromium/src/base/android/java/...),
and then wait for wasFlushDirectorySuccessful to be true.

Thoughts on this? I wish we could actually verify that the data was saved in the
data store, but this seems almost as good.

+  DCHECK_EQ(base::MessageLoop::current(), sync_loop_);
+  syncer::syncable::Directory* directory =
+      sync_manager()->GetUserShare()->directory.get();
+  if (directory != NULL) {

[Nicolas Zea, 2014/09/22 17:27:46]

The PSS conditions should protect directory from being null right? I'd get rid
of this conditional and let it crash if not, which would let us know that
something else isn't being taken into account.

+    directory->SaveChanges();
+  }
+}
+
 void SyncBackendHostCore::SendBufferedProtocolEventsAndEnableForwarding() {
   DCHECK_EQ(base::MessageLoop::current(), sync_loop_);
   forward_protocol_events_ = true;