Bug 1487115 - Fix navigator.Gamepads returns empty VR array after a page load when using gfxVRExternal r=qdot,kip

Differential Revision: https://phabricator.services.mozilla.com/D4570

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

dom/gamepad/GamepadManager.cpp

@@ -211,8 +211,15 @@ GamepadManager::GetGamepad(uint32_t aIndex) const
   return nullptr;
 }
 
+already_AddRefed<Gamepad>
+GamepadManager::GetGamepad(uint32_t aGamepadId, GamepadServiceType aServiceType) const
+{
+  return GetGamepad(GetGamepadIndexWithServiceType(aGamepadId, aServiceType));
+}
+
+
 uint32_t GamepadManager::GetGamepadIndexWithServiceType(uint32_t aIndex,
-                                                        GamepadServiceType aServiceType)
+                                                        GamepadServiceType aServiceType) const
 {
   uint32_t newIndex = 0;
 

dom/gamepad/GamepadManager.h

@@ -60,6 +60,9 @@ class GamepadManager final : public nsIObserver
   // Returns gamepad object if index exists, null otherwise
   already_AddRefed<Gamepad> GetGamepad(uint32_t aIndex) const;
 
+    // Returns gamepad object if GamepadId exists, null otherwise
+  already_AddRefed<Gamepad> GetGamepad(uint32_t aGamepadId, GamepadServiceType aServiceType) const;
+
   // Receive GamepadChangeEvent messages from parent process to fire DOM events
   void Update(const GamepadChangeEvent& aGamepadEvent);
 
@@ -132,7 +135,7 @@ class GamepadManager final : public nsIObserver
                                bool aHasSeen = true);
   // Our gamepad index has VR_GAMEPAD_IDX_OFFSET while GamepadChannelType
   // is from VRManager.
-  uint32_t GetGamepadIndexWithServiceType(uint32_t aIndex, GamepadServiceType aServiceType);
+  uint32_t GetGamepadIndexWithServiceType(uint32_t aIndex, GamepadServiceType aServiceType) const;
 
   // Gamepads connected to the system. Copies of these are handed out
   // to each window.

gfx/vr/VRDisplayClient.cpp

@@ -13,6 +13,7 @@
 #include "nsRefPtrHashtable.h"
 #include "nsString.h"
 #include "mozilla/dom/GamepadManager.h"
+#include "mozilla/dom/Gamepad.h"
 #include "mozilla/Preferences.h"
 #include "mozilla/Unused.h"
 #include "nsServiceManagerUtils.h"
@@ -169,7 +170,8 @@ VRDisplayClient::FireGamepadEvents()
     }
 
     // Send events to notify that new controllers are added
-    if (lastState.controllerName[0] == '\0') {
+    RefPtr<dom::Gamepad> existing = gamepadManager->GetGamepad(gamepadId, dom::GamepadServiceType::VR);
+    if (lastState.controllerName[0] == '\0' || !existing) {
       dom::GamepadAdded info(NS_ConvertUTF8toUTF16(state.controllerName),
                              dom::GamepadMappingType::_empty,
                              state.hand,