Bug 1498625 - Part 1: Move VRHapticThread start/end to the main thread. r=kip,froydnj

Differential Revision: https://phabricator.services.mozilla.com/D10642

--HG--
extra : moz-landing-system : lando

gfx/vr/ipc/VRParent.cpp

@@ -114,6 +114,12 @@ VRParent::Init(base::ProcessId aParentPid,
                MessageLoop* aIOLoop,
                IPC::Channel* aChannel)
 {
+  // Initialize the thread manager before starting IPC. Otherwise, messages
+  // may be posted to the main thread and we won't be able to process them.
+  if (NS_WARN_IF(NS_FAILED(nsThreadManager::get().Init()))) {
+    return false;
+  }
+
   // Now it's safe to start IPC.
   if (NS_WARN_IF(!Open(aChannel, aParentPid, aIOLoop))) {
     return false;
@@ -136,6 +142,10 @@ VRParent::Init(base::ProcessId aParentPid,
 #if defined(XP_WIN)
   DeviceManagerDx::Init();
 #endif
+  if (NS_FAILED(NS_InitMinimalXPCOM())) {
+    return false;
+  }
+
   return true;
 }
 

gfx/vr/service/OpenVRSession.cpp

@@ -157,8 +157,10 @@ OpenVRSession::Initialize(mozilla::gfx::VRSystemState& aSystemState)
     return false;
   }
 
-  StartHapticThread();
-  StartHapticTimer();
+  NS_DispatchToMainThread(NS_NewRunnableFunction(
+    "OpenVRSession::StartHapticThread", [this]() {
+      StartHapticThread();
+  }));
   
   // Succeeded
   return true;
@@ -927,17 +929,23 @@ OpenVRSession::VibrateHaptic(uint32_t aControllerIdx, uint32_t aHapticIndex,
 void
 OpenVRSession::StartHapticThread()
 {
+  MOZ_ASSERT(NS_IsMainThread());
   if (!mHapticThread) {
     mHapticThread = new VRThread(NS_LITERAL_CSTRING("VR_OpenVR_Haptics"));
   }
   mHapticThread->Start();
+  StartHapticTimer();
 }
 
 void
 OpenVRSession::StopHapticThread()
 {
   if (mHapticThread) {
-    mHapticThread->Shutdown();
+    NS_DispatchToMainThread(NS_NewRunnableFunction(
+      "mHapticThread::Shutdown",
+      [thread = mHapticThread]() {
+        thread->Shutdown();
+    }));
     mHapticThread = nullptr;
   }
 }