[Nearby] Synchronously construct service controller.

The service controller passed to ServiceControllerProxy was being
initialized asynchronously, and could occasionally be passed into
ServiceControllerProxy before being correctly initialized, causing
a segfault once accessed. This CL changes that behavior to simply
immediately initialize the service controller.

Fixed: 1147293
Change-Id: Ie4e396706b5477befca47805c8984c697a814bcd
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2527633Reviewed-by: James Vecore <vecore@google.com>
Reviewed-by: Kyle Horimoto <khorimoto@chromium.org>
Commit-Queue: Ryan Hansberry <hansberry@chromium.org>
Cr-Commit-Position: refs/heads/master@{#825958}

chrome/services/sharing/nearby/nearby_connections.cc

@@ -185,19 +185,6 @@ NearbyConnections::NearbyConnections(
       on_disconnect_(std::move(on_disconnect)),
       service_controller_(std::move(service_controller)),
       thread_task_runner_(base::ThreadTaskRunnerHandle::Get()) {
-  // Note: Some tests pass a value for |service_controller_|, but this value is
-  // expected to be null during normal operation.
-  if (!service_controller_) {
-    // Post a task which initializes |service_controller_|. This must be posted
-    // as a task instead of being completed synchrnously here because
-    // OfflineServiceController invokes NearbyConnections::GetInstance(), which
-    // requires that the instance be initialized by completing this constructor.
-    thread_task_runner_->PostTask(
-        FROM_HERE,
-        base::BindOnce(&NearbyConnections::InitializeOfflineServiceController,
-                       weak_ptr_factory_.GetWeakPtr()));
-  }
-
   nearby_connections_.set_disconnect_handler(base::BindOnce(
       &NearbyConnections::OnDisconnect, weak_ptr_factory_.GetWeakPtr()));
 
@@ -244,6 +231,15 @@ NearbyConnections::NearbyConnections(
   // There should only be one instance of NearbyConnections in a process.
   DCHECK(!g_instance);
   g_instance = this;
+
+  // Note: Some tests pass a value for |service_controller_|, but this value is
+  // expected to be null during normal operation.
+  if (!service_controller_) {
+    // OfflineServiceController indirectly invokes
+    // NearbyConnections::GetInstance(), so it must be initialized after
+    // |g_instance| is set.
+    service_controller_ = std::make_unique<OfflineServiceController>();
+  }
 }
 
 NearbyConnections::~NearbyConnections() {
@@ -253,11 +249,6 @@ NearbyConnections::~NearbyConnections() {
   g_instance = nullptr;
 }
 
-void NearbyConnections::InitializeOfflineServiceController() {
-  DCHECK(!service_controller_);
-  service_controller_ = std::make_unique<OfflineServiceController>();
-}
-
 void NearbyConnections::OnDisconnect() {
   if (on_disconnect_)
     std::move(on_disconnect_).Run();

chrome/services/sharing/nearby/nearby_connections.h

@@ -153,7 +153,6 @@ class NearbyConnections : public mojom::NearbyConnections {
  private:
   Core* GetCore(const std::string& service_id);
 
-  void InitializeOfflineServiceController();
   void OnDisconnect();
 
   mojo::Receiver<mojom::NearbyConnections> nearby_connections_;