libcamera: camera_manager: Bind CameraManager to threads

The CameraManager class uses the event dispatcher of the current thread.
This makes the CameraManager::eventDispatcher() and
CameraManager::setEventDispatcher() methods inconsistent, as they access
different event dispatcher instances depending on the calling thread.

Fix this by inheriting from the Object class, which binds the
CameraManager to a thread, and use the event dispatcher of the bound
thread.

Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Reviewed-by: Jacopo Mondi <jacopo@jmondi.org>
Reviewed-by: Niklas Söderlund <niklas.soderlund@ragnatech.se>

src/libcamera/camera_manager.cpp

@@ -248,7 +248,7 @@ CameraManager *CameraManager::instance()
  */
 void CameraManager::setEventDispatcher(std::unique_ptr<EventDispatcher> dispatcher)
 {
-	Thread::current()->setEventDispatcher(std::move(dispatcher));
+	thread()->setEventDispatcher(std::move(dispatcher));
 }
 
 /**
@@ -264,7 +264,7 @@ void CameraManager::setEventDispatcher(std::unique_ptr<EventDispatcher> dispatch
  */
 EventDispatcher *CameraManager::eventDispatcher()
 {
-	return Thread::current()->eventDispatcher();
+	return thread()->eventDispatcher();
 }
 
 } /* namespace libcamera */