Removing the subclassing of UnityAppController for iOS.

This avoids any issues when this plugin is used with  others that need
to handle deep links, etc.

Also fixes a bug when trying to sign back in after signing out.

Change-Id: Ia35f228a82c4744f83fb9955bc68366c68a828a7

Author: claywilkinson

GoogleSignInPlugin/Assets/GoogleSignIn/GoogleSignIn.cs

@@ -66,7 +66,7 @@ static GoogleSignIn() {
     public static GoogleSignInConfiguration Configuration {
       set {
         // Can set the configuration until the singleton is created.
-        if (theInstance == null || theConfiguration == value) {
+        if (theInstance == null || theConfiguration == value || theConfiguration == null) {
           theConfiguration = value;
         } else {
           throw new SignInException(GoogleSignInStatusCode.DeveloperError,
@@ -141,6 +141,7 @@ public Task<GoogleSignInUser> SignInSilently() {
     /// account to use when signing in.
     /// </remarks>
     public void SignOut() {
+      theConfiguration = null;
       impl.SignOut();
     }
 

GoogleSignInPlugin/Assets/Plugins/iOS/GoogleSignIn/GoogleSignIn.h

@@ -0,0 +1,20 @@
+/**
+ * Copyright 2017 Google Inc.
+ *
+ * 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 <GoogleSignIn/GIDSignIn.h>
+@interface GoogleSignInHandler
+    : NSObject <GIDSignInDelegate, GIDSignInUIDelegate>
+
+@end