Add FirebaseCore component interoperability. (#1437)

* Add FirebaseCore component interoperability.

This puts in place the system that will allow SDKs to register with
Core and retrieve functionalities provided by other SDKs.

* Updated documentation.

* Add copywrite, fix log messages.

* Explicitly import headers from Private dir

1 files changed, 39 insertions, 0 deletions

diff --git a/Firebase/Core/Private/FIRComponentContainerInternal.h b/Firebase/Core/Private/FIRComponentContainerInternal.h
new file mode 100644
index 0000000..bb73e7b
--- /dev/null
+++ b/Firebase/Core/Private/FIRComponentContainerInternal.h
@@ -0,0 +1,39 @@
+/*
+ * Copyright 2018 Google
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+#import <Foundation/Foundation.h>
+
+#import "FIRComponent.h"
+#import "FIRComponentContainer.h"
+
+@class FIRApp;
+
+NS_ASSUME_NONNULL_BEGIN
+
+@interface FIRComponentContainer (Private)
+
+/// Initializes a contain for a given app. This should only be called by the app itself.
+- (instancetype)initWithApp:(FIRApp *)app;
+
+/// Retrieves an instance that conforms to the specified protocol. This will return `nil` if the
+/// protocol wasn't registered, or if the instance couldn't instantiate for the provided app.
+- (nullable id)instanceForProtocol:(Protocol *)protocol NS_SWIFT_NAME(instance(for:));
+
+/// Remove all of the cached instances stored and allow them to clean up after themselves.
+- (void)removeAllCachedInstances;
+
+@end
+
+NS_ASSUME_NONNULL_END