[ReactNative] Use a single DisplayLink held by the bridge

React/Base/RCTFrameUpdate.h

@@ -0,0 +1,44 @@
+/**
+ * Copyright (c) 2015-present, Facebook, Inc.
+ * All rights reserved.
+ *
+ * This source code is licensed under the BSD-style license found in the
+ * LICENSE file in the root directory of this source tree. An additional grant
+ * of patent rights can be found in the PATENTS file in the same directory.
+ */
+
+/**
+ * Interface containing the information about the last screen refresh.
+ */
+@interface RCTFrameUpdate : NSObject
+
+/**
+ * Timestamp for the actual screen refresh
+ */
+@property (nonatomic, readonly) NSTimeInterval timestamp;
+
+/**
+ * Time since the last frame update ( >= 16.6ms )
+ */
+@property (nonatomic, readonly) NSTimeInterval deltaTime;
+
+@end
+
+/**
+ * Protocol that must be implemented for subscribing to display refreshes (DisplayLink updates)
+ */
+@protocol RCTFrameUpdateObserver <NSObject>
+
+/**
+ * Method called on every screen refresh (if paused != YES)
+ */
+- (void)didUpdateFrame:(RCTFrameUpdate *)update;
+
+@optional
+
+/**
+ * Synthesize and set to true to pause the calls to -[didUpdateFrame:]
+ */
+@property (nonatomic, assign, getter=isPaused) BOOL paused;
+
+@end