WebApp: Call RegistryOpenedCallback asynchronously.

We should break down this synchronous call chain:

web_app::WebAppSyncBridge::CommitUpdate()
web_app::ScopedRegistryUpdate::~ScopedRegistryUpdate()
web_app::WebAppInstallFinalizer::UninstallWebApp()
web_app::WebAppInstallFinalizer::UninstallWebAppOrRemoveSource()
web_app::WebAppInstallFinalizer::UninstallExternalWebApp()
web_app::InstallFinalizer::UninstallExternalWebAppByUrl()
web_app::PendingAppManagerImpl::UninstallApps()
web_app::PendingAppManager::SynchronizeInstalledApps()
web_app::ExternalWebAppManager::OnScanForExternalWebApps()
web_app::ExternalWebAppManager::ScanForExternalWebApps()
web_app::ExternalWebAppManager::Start()
web_app::WebAppProvider::OnRegistryControllerReady()
web_app::WebAppSyncBridge::OnDatabaseOpened()
web_app::WebAppDatabase::OnAllMetadataRead()
syncer::ModelTypeStoreImpl::ReadAllMetadataDone()

WebAppSyncBridge::OnDatabaseOpened() must not cause immediate
WebAppSyncBridge::CommitUpdate() on same `this`.

Bug: 1084939
Change-Id: Ib32c52780a647a0985418c0f92985f041869f104
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2212236Reviewed-by: Eric Willigers <ericwilligers@chromium.org>
Commit-Queue: Alexey Baskakov <loyso@chromium.org>
Cr-Commit-Position: refs/heads/master@{#771473}

chrome/browser/web_applications/web_app_database.cc

@@ -11,6 +11,7 @@
 #include "base/bind.h"
 #include "base/callback.h"
 #include "base/stl_util.h"
+#include "base/threading/sequenced_task_runner_handle.h"
 #include "chrome/browser/web_applications/components/web_app_helpers.h"
 #include "chrome/browser/web_applications/components/web_app_utils.h"
 #include "chrome/browser/web_applications/web_app.h"
@@ -414,8 +415,11 @@ void WebAppDatabase::OnAllMetadataRead(
       registry.emplace(app_id, std::move(web_app));
   }
 
-  std::move(callback).Run(std::move(registry), std::move(metadata_batch));
   opened_ = true;
+
+  base::SequencedTaskRunnerHandle::Get()->PostTask(
+      FROM_HERE, base::BindOnce(std::move(callback), std::move(registry),
+                                std::move(metadata_batch)));
 }
 
 void WebAppDatabase::OnDataWritten(

chrome/browser/web_applications/web_app_sync_bridge.cc

@@ -13,6 +13,7 @@
 #include "base/containers/flat_set.h"
 #include "base/logging.h"
 #include "base/optional.h"
+#include "base/threading/sequenced_task_runner_handle.h"
 #include "base/util/type_safety/pass_key.h"
 #include "chrome/browser/web_applications/components/web_app_helpers.h"
 #include "chrome/browser/web_applications/components/web_app_utils.h"
@@ -315,9 +316,11 @@ void WebAppSyncBridge::OnDatabaseOpened(
   change_processor()->ModelReadyToSync(std::move(metadata_batch));
 
   registrar_->InitRegistry(std::move(registry));
-  std::move(callback).Run();
 
   MaybeInstallAppsInSyncInstall();
+
+  base::SequencedTaskRunnerHandle::Get()->PostTask(FROM_HERE,
+                                                   std::move(callback));
 }
 
 void WebAppSyncBridge::OnDataWritten(CommitCallback callback, bool success) {