Fix access violation in drive sync engine.

The introduction of team drives means that calling
DriveAPIService::GetChangeList can return a ChangeList object that contains both
FileResource and TeamDriveResource entries. The sync engine code is not
TeamDriveResource aware and assumes that ChangeList can only contain
FileResource entries, and calling ChangeResource::File() will return a nullptr
that later causes an AV in PopulateFileDetailsByFileResource.

This CL filters out TeamDriveResource from the ChangeList object. Verified with
new unit test.

Bug: 850228
Change-Id: I1d8f4e8a99df8b8b04683eccaaceae4843020bda
Reviewed-on: https://chromium-review.googlesource.com/1212366
Commit-Queue: Stuart Langley <slangley@chromium.org>
Reviewed-by: Kinuko Yasuda <kinuko@chromium.org>
Cr-Commit-Position: refs/heads/master@{#589826}

chrome/browser/sync_file_system/drive_backend/fake_drive_service_helper.cc

@@ -350,5 +350,10 @@ base::FilePath FakeDriveServiceHelper::WriteToTempFile(
   return temp_file;
 }
 
+void FakeDriveServiceHelper::AddTeamDrive(const std::string& team_drive_id,
+                                          const std::string& team_drive_name) {
+  fake_drive_service_->AddTeamDrive(team_drive_id, team_drive_name);
+}
+
 }  // namespace drive_backend
 }  // namespace sync_file_system

chrome/browser/sync_file_system/drive_backend/fake_drive_service_helper.h

@@ -78,6 +78,9 @@ class FakeDriveServiceHelper {
   google_apis::DriveApiErrorCode GetAboutResource(
       std::unique_ptr<google_apis::AboutResource>* about_resource);
 
+  void AddTeamDrive(const std::string& team_drive_id,
+                    const std::string& team_drive_name);
+
   base::FilePath base_dir_path() { return base_dir_.GetPath(); }
 
  private:

chrome/browser/sync_file_system/drive_backend/list_changes_task.cc

@@ -75,10 +75,23 @@ void ListChangesTask::DidListChanges(
     return;
   }
 
-  change_list_.reserve(change_list_.size() +
-                       change_list->mutable_items()->size());
-  std::move(change_list->mutable_items()->begin(),
-            change_list->mutable_items()->end(),
+  auto* mutable_items = change_list->mutable_items();
+
+  // google_apis::ChangeList can contain both FileResource and TeamDriveResource
+  // entries. We only care about FileResource entries, so filter out any entries
+  // that are TeamDriveReasource.
+  mutable_items->erase(
+      std::remove_if(
+          mutable_items->begin(), mutable_items->end(),
+          [](const auto& change_resource) {
+            return change_resource->type() ==
+                   google_apis::ChangeResource::ChangeType::TEAM_DRIVE;
+          }),
+      mutable_items->end());
+
+  change_list_.reserve(change_list_.size() + mutable_items->size());
+
+  std::move(mutable_items->begin(), mutable_items->end(),
             std::back_inserter(change_list_));
   change_list->mutable_items()->clear();
 

chrome/browser/sync_file_system/drive_backend/list_changes_task_unittest.cc

@@ -242,5 +242,20 @@ TEST_F(ListChangesTaskTest, UnderTrackedFolder) {
   EXPECT_EQ(num_dirty_trackers + 4, CountDirtyTracker());
 }
 
+TEST_F(ListChangesTaskTest, TeamDriveChangeInChangeList) {
+  size_t num_dirty_trackers = CountDirtyTracker();
+
+  SetUpChangesInFolder(app_root_folder_id());
+
+  // Adding a team drive will return a TeamDriveResource entry when the
+  // change list is retrieved.
+  fake_drive_service_helper()->AddTeamDrive("team_drive_id", "team_drive_name");
+
+  EXPECT_EQ(SYNC_STATUS_OK, RunTask(std::unique_ptr<SyncTask>(
+                                new ListChangesTask(GetSyncEngineContext()))));
+
+  EXPECT_EQ(num_dirty_trackers + 4, CountDirtyTracker());
+}
+
 }  // namespace drive_backend
 }  // namespace sync_file_system