Persist Directory to disk when the app is backgrounded.

chrome/browser/sync/profile_sync_service_android.cc

 // Copyright 2013 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.
 
 #include "chrome/browser/sync/profile_sync_service_android.h"
 
 #include "base/android/jni_android.h"
 #include "base/android/jni_string.h"
 #include "base/bind.h"
 #include "base/i18n/time_formatting.h"
@@ skipping 163 matching lines @@
 
 void ProfileSyncServiceAndroid::SignOutSync(JNIEnv* env, jobject) {
   DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
   DCHECK(profile_);
   sync_service_->DisableForUser();
 
   // Need to clear suppress start flag manually
   sync_prefs_->SetStartSuppressed(false);
 }
 
+void ProfileSyncServiceAndroid::FlushDirectory(JNIEnv* env, jobject) {
+  if (sync_service_ != nullptr) {

[nyquist, 2014/09/10 17:43:09]

Use NULL instead of nullptr.

Also, DCHECK for UI thread?

And thirdly, is it common for this to be null? If not, there is already a DCHECK
in the constructor for this. Since this is not static, I would assume that the
service would always be there?

[maxbogue, 2014/09/10 20:11:02]

Added the DCHECK. I've removed the null check entirely; I think I only added it
trying to fix the crash that the other null check prevented.

+    sync_service_->FlushDirectory();
+  }
+}
+
 ScopedJavaLocalRef<jstring> ProfileSyncServiceAndroid::QuerySyncStatusSummary(
     JNIEnv* env, jobject) {
   DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
   DCHECK(profile_);
   std::string status(sync_service_->QuerySyncStatusSummaryString());
   return ConvertUTF8ToJavaString(env, status);
 }
 
 jboolean ProfileSyncServiceAndroid::SetSyncSessionsId(
     JNIEnv* env, jobject obj, jstring tag) {
@@ skipping 344 matching lines @@
   ProfileSyncServiceAndroid* profile_sync_service_android =
       new ProfileSyncServiceAndroid(env, obj);
   profile_sync_service_android->Init();
   return reinterpret_cast<intptr_t>(profile_sync_service_android);
 }
 
 // static
 bool ProfileSyncServiceAndroid::Register(JNIEnv* env) {
   return RegisterNativesImpl(env);
 }