[Android] Stop saving the legacy Sync Directory when app backgrounded

This logically reverts the old https://codereview.chromium.org/551843003
because meanwhile the Sync Directory has been deprecated in favor of a
new codepath, Unified Sync and Storage (USS).

Change-Id: I80e66c304b76a8d9edffe1a4657ba0c2513f2ff4
Bug: 923287
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2250042Reviewed-by: Marc Treib <treib@chromium.org>
Commit-Queue: Mikel Astiz <mastiz@chromium.org>
Cr-Commit-Position: refs/heads/master@{#779748}

chrome/android/java/src/org/chromium/chrome/browser/sync/ProfileSyncService.java

@@ -357,14 +357,6 @@ public class ProfileSyncService {
                 mNativeProfileSyncServiceAndroid, ProfileSyncService.this, allowed);
     }
 
-    /**
-     * Flushes the sync directory to disk.
-     */
-    public void flushDirectory() {
-        ProfileSyncServiceJni.get().flushDirectory(
-                mNativeProfileSyncServiceAndroid, ProfileSyncService.this);
-    }
-
     /**
      * Returns the actual passphrase type being used for encryption. The sync engine must be
      * running (isEngineInitialized() returns true) before calling this function.
@@ -654,7 +646,6 @@ public class ProfileSyncService {
         void requestStop(long nativeProfileSyncServiceAndroid, ProfileSyncService caller);
         void setSyncAllowedByPlatform(
                 long nativeProfileSyncServiceAndroid, ProfileSyncService caller, boolean allowed);
-        void flushDirectory(long nativeProfileSyncServiceAndroid, ProfileSyncService caller);
         void setSyncSessionsId(
                 long nativeProfileSyncServiceAndroid, ProfileSyncService caller, String tag);
         int getAuthError(long nativeProfileSyncServiceAndroid, ProfileSyncService caller);

chrome/android/java/src/org/chromium/chrome/browser/sync/SyncController.java

@@ -5,14 +5,10 @@
 package org.chromium.chrome.browser.sync;
 
 import android.annotation.SuppressLint;
-import android.app.Activity;
 
 import androidx.annotation.Nullable;
 import androidx.annotation.VisibleForTesting;
 
-import org.chromium.base.ActivityState;
-import org.chromium.base.ApplicationStatus;
-import org.chromium.base.ApplicationStatus.ActivityStateListener;
 import org.chromium.base.Log;
 import org.chromium.base.ThreadUtils;
 import org.chromium.base.metrics.RecordHistogram;
@@ -79,16 +75,6 @@ public class SyncController implements ProfileSyncService.SyncStateChangedListen
 
         updateSyncStateFromAndroid();
 
-        // When the application gets paused, tell sync to flush the directory to disk.
-        ApplicationStatus.registerStateListenerForAllActivities(new ActivityStateListener() {
-            @Override
-            public void onActivityStateChange(Activity activity, int newState) {
-                if (newState == ActivityState.PAUSED) {
-                    mProfileSyncService.flushDirectory();
-                }
-            }
-        });
-
         IdentityServicesProvider.get().getSigninManager().addSignInStateObserver(
                 new SigninManager.SignInStateObserver() {
                     @Override

chrome/android/javatests/src/org/chromium/chrome/browser/sync/SyncTest.java

@@ -5,8 +5,6 @@
 package org.chromium.chrome.browser.sync;
 
 import android.accounts.Account;
-import android.app.Activity;
-import android.support.test.InstrumentationRegistry;
 
 import androidx.test.filters.LargeTest;
 
@@ -15,8 +13,6 @@ import org.junit.Rule;
 import org.junit.Test;
 import org.junit.runner.RunWith;
 
-import org.chromium.base.ActivityState;
-import org.chromium.base.ApplicationStatus;
 import org.chromium.base.test.util.CommandLineFlags;
 import org.chromium.base.test.util.DisabledTest;
 import org.chromium.base.test.util.Feature;
@@ -43,23 +39,6 @@ public class SyncTest {
 
     private static final String TAG = "SyncTest";
 
-    @Test
-    @LargeTest
-    @Feature({"Sync"})
-    public void testFlushDirectoryDoesntBreakSync() {
-        mSyncTestRule.setUpAccountAndSignInForTesting();
-        final Activity activity = mSyncTestRule.getActivity();
-
-        InstrumentationRegistry.getInstrumentation().runOnMainSync(new Runnable() {
-            @Override
-            public void run() {
-                ApplicationStatus.onStateChangeForTesting(activity, ActivityState.PAUSED);
-            }
-        });
-
-        // TODO(pvalenzuela): When available, check that sync is still functional.
-    }
-
     @Test
     @LargeTest
     @Feature({"Sync"})

chrome/browser/sync/profile_sync_service_android.cc

@@ -360,12 +360,6 @@ jlong ProfileSyncServiceAndroid::GetExplicitPassphraseTime(
   return passphrase_time.ToJavaTime();
 }
 
-void ProfileSyncServiceAndroid::FlushDirectory(JNIEnv* env,
-                                               const JavaParamRef<jobject>&) {
-  DCHECK_CURRENTLY_ON(BrowserThread::UI);
-  sync_service_->FlushDirectory();
-}
-
 void ProfileSyncServiceAndroid::GetAllNodes(
     JNIEnv* env,
     const JavaParamRef<jobject>& obj,

chrome/browser/sync/profile_sync_service_android.h

@@ -116,8 +116,6 @@ class ProfileSyncServiceAndroid : public syncer::SyncServiceObserver {
       const base::android::JavaParamRef<jobject>&);
   jlong GetExplicitPassphraseTime(JNIEnv* env,
                                   const base::android::JavaParamRef<jobject>&);
-  void FlushDirectory(JNIEnv* env,
-                      const base::android::JavaParamRef<jobject>& obj);
   void GetAllNodes(JNIEnv* env,
                    const base::android::JavaParamRef<jobject>& obj,
                    const base::android::JavaParamRef<jobject>& callback);

components/sync/driver/glue/sync_engine_impl.cc

@@ -240,12 +240,6 @@ void SyncEngineImpl::GetModelSafeRoutingInfo(ModelSafeRoutingInfo* out) const {
   }
 }
 
-void SyncEngineImpl::FlushDirectory() const {
-  DCHECK(IsInitialized());
-  sync_task_runner_->PostTask(
-      FROM_HERE, base::BindOnce(&SyncEngineBackend::SaveChanges, backend_));
-}
-
 void SyncEngineImpl::RequestBufferedProtocolEventsAndEnableForwarding() {
   sync_task_runner_->PostTask(
       FROM_HERE,

components/sync/driver/glue/sync_engine_impl.h

@@ -81,7 +81,6 @@ class SyncEngineImpl : public SyncEngine, public InvalidationHandler {
   void HasUnsyncedItemsForTest(
       base::OnceCallback<void(bool)> cb) const override;
   void GetModelSafeRoutingInfo(ModelSafeRoutingInfo* out) const override;
-  void FlushDirectory() const override;
   void RequestBufferedProtocolEventsAndEnableForwarding() override;
   void DisableProtocolEventForwarding() override;
   void EnableDirectoryTypeDebugInfoForwarding() override;

components/sync/driver/profile_sync_service.cc

@@ -1991,13 +1991,6 @@ void ProfileSyncService::OverrideNetworkForTest(
   }
 }
 
-void ProfileSyncService::FlushDirectory() const {
-  DCHECK_CALLED_ON_VALID_SEQUENCE(sequence_checker_);
-  if (engine_ && engine_->IsInitialized()) {
-    engine_->FlushDirectory();
-  }
-}
-
 bool ProfileSyncService::IsPassphrasePrompted() const {
   return sync_prefs_.IsPassphrasePrompted();
 }

components/sync/driver/profile_sync_service.h

@@ -221,11 +221,6 @@ class ProfileSyncService : public SyncService,
   // once (before this object is destroyed).
   void Shutdown() override;
 
-  // This triggers a Directory::SaveChanges() call on the sync thread.
-  // It should be used to persist data to disk when the process might be
-  // killed in the near future.
-  void FlushDirectory() const;
-
   bool IsPassphrasePrompted() const;
   void SetPassphrasePrompted(bool prompted);
 

components/sync/engine/fake_sync_engine.cc

@@ -81,8 +81,6 @@ void FakeSyncEngine::HasUnsyncedItemsForTest(
 
 void FakeSyncEngine::GetModelSafeRoutingInfo(ModelSafeRoutingInfo* out) const {}
 
-void FakeSyncEngine::FlushDirectory() const {}
-
 void FakeSyncEngine::RequestBufferedProtocolEventsAndEnableForwarding() {}
 
 void FakeSyncEngine::DisableProtocolEventForwarding() {}

components/sync/engine/fake_sync_engine.h

@@ -77,8 +77,6 @@ class FakeSyncEngine : public SyncEngine {
 
   void GetModelSafeRoutingInfo(ModelSafeRoutingInfo* out) const override;
 
-  void FlushDirectory() const override;
-
   void RequestBufferedProtocolEventsAndEnableForwarding() override;
   void DisableProtocolEventForwarding() override;
 

components/sync/engine/mock_sync_engine.h

@@ -53,7 +53,6 @@ class MockSyncEngine : public SyncEngine {
   MOCK_CONST_METHOD1(HasUnsyncedItemsForTest,
                      void(base::OnceCallback<void(bool)>));
   MOCK_CONST_METHOD1(GetModelSafeRoutingInfo, void(ModelSafeRoutingInfo*));
-  MOCK_CONST_METHOD0(FlushDirectory, void());
   MOCK_METHOD0(RequestBufferedProtocolEventsAndEnableForwarding, void());
   MOCK_METHOD0(DisableProtocolEventForwarding, void());
   MOCK_METHOD0(EnableDirectoryTypeDebugInfoForwarding, void());

components/sync/engine/sync_engine.h

@@ -168,9 +168,6 @@ class SyncEngine : public ModelTypeConfigurer {
 
   virtual void GetModelSafeRoutingInfo(ModelSafeRoutingInfo* out) const = 0;
 
-  // Send a message to the sync thread to persist the Directory to disk.
-  virtual void FlushDirectory() const = 0;
-
   // Requests that the backend forward to the fronent any protocol events in
   // its buffer and begin forwarding automatically from now on.  Repeated calls
   // to this function may result in the same events being emitted several