Push down the deviceController ivar into MTRDevice subclasses.

This allows them to store the specific controller types they are associated
with, which will allow us to move APIs that only make sense for a particular
type to that type.

src/darwin/Framework/CHIP/MTRDevice.mm

@@ -282,12 +282,14 @@ @implementation MTRDevice {
     NSNumber * _Nullable _allNetworkFeatures;
 }
 
+// deviceController getter is implemented by subclasses.
+@dynamic deviceController;
+
 - (instancetype)initForSubclassesWithNodeID:(NSNumber *)nodeID controller:(MTRDeviceController *)controller
 {
     if (self = [super init]) {
         _lock = OS_UNFAIR_LOCK_INIT;
         _delegates = [NSMutableSet set];
-        _deviceController = controller;
         _nodeID = nodeID;
         _state = MTRDeviceStateUnknown;
     }
@@ -606,7 +608,7 @@ - (void)_persistClusterData
     // storage implementation, which will try to read them later.  Make sure
     // we snapshot the state here instead of handing out live copies.
     NSDictionary<MTRClusterPath *, MTRDeviceClusterData *> * clusterData = [self _clusterDataToPersistSnapshot];
-    [_deviceController.controllerDataStore storeClusterData:clusterData forNodeID:_nodeID];
+    [self.deviceController.controllerDataStore storeClusterData:clusterData forNodeID:_nodeID];
     for (MTRClusterPath * clusterPath in _clusterDataToPersist) {
         [_persistedClusterData setObject:_clusterDataToPersist[clusterPath] forKey:clusterPath];
         [_persistedClusters addObject:clusterPath];
@@ -849,7 +851,7 @@ - (void)_reconcilePersistedClustersWithStorage
 
     NSMutableSet * clusterPathsToRemove = [NSMutableSet set];
     for (MTRClusterPath * clusterPath in _persistedClusters) {
-        MTRDeviceClusterData * data = [_deviceController.controllerDataStore getStoredClusterDataForNodeID:_nodeID endpointID:clusterPath.endpoint clusterID:clusterPath.cluster];
+        MTRDeviceClusterData * data = [self.deviceController.controllerDataStore getStoredClusterDataForNodeID:_nodeID endpointID:clusterPath.endpoint clusterID:clusterPath.cluster];
         if (!data) {
             [clusterPathsToRemove addObject:clusterPath];
         }
@@ -884,13 +886,13 @@ - (nullable MTRDeviceClusterData *)_clusterDataForPath:(MTRClusterPath *)cluster
         return nil;
     }
 
-    NSAssert(_deviceController.controllerDataStore != nil,
+    NSAssert(self.deviceController.controllerDataStore != nil,
         @"How can _persistedClusters have an entry if we have no persistence?");
     NSAssert(_persistedClusterData != nil,
         @"How can _persistedClusterData not exist if we have persisted clusters?");
 
     // Page in the stored value for the data.
-    MTRDeviceClusterData * data = [_deviceController.controllerDataStore getStoredClusterDataForNodeID:_nodeID endpointID:clusterPath.endpoint clusterID:clusterPath.cluster];
+    MTRDeviceClusterData * data = [self.deviceController.controllerDataStore getStoredClusterDataForNodeID:_nodeID endpointID:clusterPath.endpoint clusterID:clusterPath.cluster];
     MTR_LOG("%@ cluster path %@ cache miss - load from storage success %@", self, clusterPath, MTR_YES_NO(data));
     if (data != nil) {
         [_persistedClusterData setObject:data forKey:clusterPath];

src/darwin/Framework/CHIP/MTRDevice_Concrete.mm

@@ -272,6 +272,8 @@ - (BOOL)unitTestSuppressTimeBasedReachabilityChanges:(MTRDevice *)device;
 #endif
 
 @implementation MTRDevice_Concrete {
+    MTRDeviceController_Concrete * _deviceController;
+
 #ifdef DEBUG
     NSUInteger _unitTestAttributesReportedSinceLastCheck;
 #endif
@@ -365,6 +367,7 @@ - (instancetype)initWithNodeID:(NSNumber *)nodeID controller:(MTRDeviceControlle
 {
     // `super` was NSObject, is now MTRDevice.  MTRDevice hides its `init`
     if (self = [super initForSubclassesWithNodeID:nodeID controller:controller]) {
+        _deviceController = controller;
         _timeSyncLock = OS_UNFAIR_LOCK_INIT;
         _descriptionLock = OS_UNFAIR_LOCK_INIT;
         _fabricIndex = controller.fabricIndex;
@@ -465,6 +468,11 @@ - (NSString *)description
         stringWithFormat:@"<%@: %p, node: %016llX-%016llX (%llu), VID: %@, PID: %@, WiFi: %@, Thread: %@, state: %@, last subscription attempt wait: %lus, queued work: %lu, last report: %@%@, last subscription failure: %@%@, controller: %@>", NSStringFromClass(self.class), self, _deviceController.compressedFabricID.unsignedLongLongValue, _nodeID.unsignedLongLongValue, _nodeID.unsignedLongLongValue, vid, pid, wifi, thread, InternalDeviceStateString(internalDeviceState), static_cast<unsigned long>(lastSubscriptionAttemptWait), static_cast<unsigned long>(_asyncWorkQueue.itemCount), mostRecentReportTime, reportAge, lastSubscriptionFailureTime, subscriptionFailureAge, _deviceController.uniqueIdentifier];
 }
 
+- (nullable MTRDeviceController *)deviceController
+{
+    return _deviceController;
+}
+
 - (NSDictionary *)_internalProperties
 {
     NSMutableDictionary * properties = [NSMutableDictionary dictionary];

src/darwin/Framework/CHIP/MTRDevice_Internal.h

@@ -116,10 +116,6 @@ MTR_DIRECT_MEMBERS
     // Our node ID, with the ivar declared explicitly so it's accessible to
     // subclasses.
     NSNumber * _nodeID;
-
-    // Our controller.  Declared nullable because our property is, though in
-    // practice it does not look like we ever set it to nil.
-    MTRDeviceController * _Nullable _deviceController;
 }
 
 - (instancetype)initForSubclassesWithNodeID:(NSNumber *)nodeID controller:(MTRDeviceController *)controller;

src/darwin/Framework/CHIP/MTRDevice_XPC.mm

@@ -80,14 +80,16 @@
                                   : [[self deviceController] uniqueIdentifier] nodeID                                                                           \
                                   : [self nodeID])
 
-@implementation MTRDevice_XPC
+@implementation MTRDevice_XPC {
+    MTRDeviceController_XPC * _deviceController;
+}
 
 @synthesize _internalState;
 
 - (instancetype)initWithNodeID:(NSNumber *)nodeID controller:(MTRDeviceController_XPC *)controller
 {
     if (self = [super initForSubclassesWithNodeID:nodeID controller:controller]) {
-        // Nothing else to do, all set.
+        _deviceController = controller;
     }
 
     return self;
@@ -131,6 +133,11 @@ - (NSString *)description
         _deviceController.uniqueIdentifier];
 }
 
+- (nullable MTRDeviceController *)deviceController
+{
+    return _deviceController;
+}
+
 #pragma mark - Client Callbacks (MTRDeviceDelegate)
 
 // required methods for MTRDeviceDelegates