Expose SurfaceID as part ReactRootView

Summary:
This diff exposes the surfaceID as part of ReactRootView.

Changelog: [internal]

Reviewed By: JoshuaGross

Differential Revision: D18474014

fbshipit-source-id: 98f651b211d3cc4df88c6b1eb257bc12129eff57

ReactAndroid/src/main/java/com/facebook/react/uimanager/ReactRoot.java

@@ -48,4 +48,13 @@ public interface ReactRoot {
 
   /** Sets a flag that determines whether to log that content appeared on next view added. */
   void setShouldLogContentAppeared(boolean shouldLogContentAppeared);
+
+  /**
+   * @return a {@link String} that represents the root js application that is being rendered with
+   *     this {@link ReactRoot}
+   * @deprecated We recommend to not use this method as it is will be replaced in the near future.
+   */
+  @Deprecated
+  @Nullable
+  String getSurfaceID();
 }