Add configuration functions for HTTP cache type to Obj-C and C++

components/cronet/ios/Cronet.h

 // Copyright 2016 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.
 
 #import <Foundation/Foundation.h>
 
 #include "bidirectional_stream_c.h"
 
 // TODO(mef): Remove this header after transition to bidirectional_stream_c.h
 // See crbug.com/650462 for details.
 #include "cronet_c_for_grpc.h"
 
+// Type of HTTP cache; public interface to private implementation defined in
+// URLRequestContextConfig class.
+typedef NS_ENUM(NSInteger, CRNHttpCacheType) {
+  // Disabled HTTP cache.  Some data may still be temporarily stored in memory.
+  CRNHttpCacheTypeDisabled,
+  // Enable on-disk HTTP cache, including HTTP data.
+  CRNHttpCacheTypeDisk,
+  // Enable in-memory cache, including HTTP data.
+  CRNHttpCacheTypeMemory,
+};
+
 // A block, that takes a request, and returns YES if the request should
 // be handled.
 typedef BOOL (^RequestFilterBlock)(NSURLRequest* request);
 
 // Interface for installing Cronet.
 // TODO(gcasto): Should this macro be separate from the one defined in
 // bidirectional_stream_c.h?
 GRPC_SUPPORT_EXPORT
 @interface Cronet : NSObject
 
 // Sets whether HTTP/2 should be supported by CronetEngine. This method only has
 // any effect before |start| is called.
 + (void)setHttp2Enabled:(BOOL)http2Enabled;
 
 // Sets whether QUIC should be supported by CronetEngine. This method only has
 // any effect before |start| is called.
 + (void)setQuicEnabled:(BOOL)quicEnabled;
 
+// Set HTTP Cache type to be used by CronetEngine.  This method only has any
+// effect before |start| is called.  See HttpCacheType enum for available
+// options.
++ (void)setHttpCacheType:(CRNHttpCacheType)httpCacheType;
+
 // Adds hint that host supports QUIC on altPort. This method only has any effect
 // before |start| is called.
 + (void)addQuicHint:(NSString*)host port:(int)port altPort:(int)altPort;
 
 // Sets the User-Agent request header string to be sent with all requests.
 // If |partial| is set to YES, then actual user agent value is based on device
 // model, OS version, and |userAgent| argument. For example "Foo/3.0.0.0" is
 // sent as "Mozilla/5.0 (iPhone; CPU iPhone OS 9_3 like Mac OS X)
 // AppleWebKit/601.1 (KHTML, like Gecko) Foo/3.0.0.0 Mobile/15G31
 // Safari/601.1.46".
@@ skipping 71 matching lines @@
 
 // Sets Host Resolver Rules for testing.
 // This method must be called after |start| has been called.
 + (void)setHostResolverRulesForTesting:(NSString*)hostResolverRulesForTesting;
 
 // Enables TestCertVerifier which accepts all certificates for testing.
 // This method only has any effect before |start| is called.
 + (void)enableTestCertVerifierForTesting;
 
 @end