Fix include guards of files in src/ios.

ios/crnet/CrNet.h

 // Copyright 2014 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
+#ifndef IOS_CRNET_CRNET_H_
+#define IOS_CRNET_CRNET_H_
+
 #import <Foundation/Foundation.h>
 
 // A block, that takes a request, and returns YES if the request should
 // be handled.
 typedef BOOL(^RequestFilterBlock)(NSURLRequest *request);
 
 
 // A callback, called when the clearCache message has completed. The |errorCode|
 // is a network stack error code indicating whether the clear request succeeded
 // or not. Even if the request failed, the cache may have been cleared anyway,
@@ skipping 110 matching lines @@
 
 // Returns the full user-agent that the stack uses.
 // This is the exact string servers will see.
 + (NSString *)userAgent;
 
 // Clears CrNet's http cache. The supplied callback, if not nil, is run on an
 // unspecified thread.
 + (void)clearCacheWithCompletionCallback:(ClearCacheCallback)completionBlock;
 
 @end
+
+#endif  // IOS_CRNET_CRNET_H_