[Sync::USS] BookmarkProc. should have weak_ptr_factory for the worker

Before this patch:
BookmarkModelTypeProcessor has one weak_ptr_facotry used for both
the controller and the worker. This resulted in the worker having a
processor ptr while the model error isn't yet propagated.

After this patch:
The BookmarkModelTypeProcessor has dedicated weak_ptr_factory for the
worker such that in case of model error, it gets invalidated directly
while leaving the other weak_ptr_factory for the controller intact.

Bug: 516866
Change-Id: If0d9759e0cba7e5b00879646f9072522cbdb866f
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1635511
Auto-Submit: Mohamed Amir Yosef <mamir@chromium.org>
Commit-Queue: Mikel Astiz <mastiz@chromium.org>
Reviewed-by: Mikel Astiz <mastiz@chromium.org>
Cr-Commit-Position: refs/heads/master@{#664724}

components/sync_bookmarks/bookmark_model_type_processor.cc

@@ -145,7 +145,9 @@ std::string ComputeServerDefinedUniqueTagForDebugging(
 
 BookmarkModelTypeProcessor::BookmarkModelTypeProcessor(
     BookmarkUndoService* bookmark_undo_service)
-    : bookmark_undo_service_(bookmark_undo_service), weak_ptr_factory_(this) {}
+    : bookmark_undo_service_(bookmark_undo_service),
+      weak_ptr_factory_for_controller_(this),
+      weak_ptr_factory_for_worker_(this) {}
 
 BookmarkModelTypeProcessor::~BookmarkModelTypeProcessor() {
   if (bookmark_model_ && bookmark_model_observer_) {
@@ -170,6 +172,7 @@ void BookmarkModelTypeProcessor::ConnectSync(
 void BookmarkModelTypeProcessor::DisconnectSync() {
   DCHECK_CALLED_ON_VALID_SEQUENCE(sequence_checker_);
 
+  weak_ptr_factory_for_worker_.InvalidateWeakPtrs();
   if (!worker_) {
     return;
   }
@@ -370,7 +373,7 @@ size_t BookmarkModelTypeProcessor::EstimateMemoryUsage() const {
 base::WeakPtr<syncer::ModelTypeControllerDelegate>
 BookmarkModelTypeProcessor::GetWeakPtr() {
   DCHECK_CALLED_ON_VALID_SEQUENCE(sequence_checker_);
-  return weak_ptr_factory_.GetWeakPtr();
+  return weak_ptr_factory_for_controller_.GetWeakPtr();
 }
 
 void BookmarkModelTypeProcessor::OnSyncStarting(
@@ -427,7 +430,7 @@ void BookmarkModelTypeProcessor::ConnectIfReady() {
   }
   activation_context->type_processor =
       std::make_unique<syncer::ModelTypeProcessorProxy>(
-          weak_ptr_factory_.GetWeakPtr(),
+          weak_ptr_factory_for_worker_.GetWeakPtr(),
           base::SequencedTaskRunnerHandle::Get());
   std::move(start_callback_).Run(std::move(activation_context));
 }
@@ -464,7 +467,8 @@ void BookmarkModelTypeProcessor::OnSyncStopping(
   }
 
   // Do not let any delayed callbacks to be called.
-  weak_ptr_factory_.InvalidateWeakPtrs();
+  weak_ptr_factory_for_controller_.InvalidateWeakPtrs();
+  weak_ptr_factory_for_worker_.InvalidateWeakPtrs();
 }
 
 void BookmarkModelTypeProcessor::NudgeForCommitIfNeeded() {

components/sync_bookmarks/bookmark_model_type_processor.h

@@ -163,7 +163,12 @@ class BookmarkModelTypeProcessor : public syncer::ModelTypeProcessor,
 
   std::unique_ptr<BookmarkModelObserverImpl> bookmark_model_observer_;
 
-  base::WeakPtrFactory<BookmarkModelTypeProcessor> weak_ptr_factory_;
+  // WeakPtrFactory for this processor for ModelTypeController.
+  base::WeakPtrFactory<BookmarkModelTypeProcessor>
+      weak_ptr_factory_for_controller_;
+
+  // WeakPtrFactory for this processor which will be sent to sync thread.
+  base::WeakPtrFactory<BookmarkModelTypeProcessor> weak_ptr_factory_for_worker_;
 
   DISALLOW_COPY_AND_ASSIGN(BookmarkModelTypeProcessor);
 };