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

components/cronet/ios/Cronet.h

Index: components/cronet/ios/Cronet.h
diff --git a/components/cronet/ios/Cronet.h b/components/cronet/ios/Cronet.h
index 446cec1557913c9abe6c469fe80ea1bef74eb36d..987dd7bba450d83f6d949e2f8b11c5ac0457e28c 100644
--- a/components/cronet/ios/Cronet.h
+++ b/components/cronet/ios/Cronet.h
@@ -5,11 +5,14 @@
 #import <Foundation/Foundation.h>
 
 #include "bidirectional_stream_c.h"
+#include "components/cronet/url_request_context_config.h"

[mef, 2017/01/18 22:39:51]

Cronet.h is public header, distributed with Cronet framework, but
url_request_context_config.h is not.

We should define ObjC constants or enums here with proper public comments and
map them internally into cronet::URLRequestContextConfig::HttpCacheType.

[lilyhoughton, 2017/01/19 16:17:15]

Done.

 
 // TODO(mef): Remove this header after transition to bidirectional_stream_c.h
 // See crbug.com/650462 for details.
 #include "cronet_c_for_grpc.h"
 
+typedef cronet::URLRequestContextConfig::HttpCacheType HttpCacheType;
+
 // A block, that takes a request, and returns YES if the request should
 // be handled.
 typedef BOOL (^RequestFilterBlock)(NSURLRequest* request);
@@ -28,6 +31,10 @@ GRPC_SUPPORT_EXPORT
 // any effect before |start| is called.
 + (void)setQuicEnabled:(BOOL)quicEnabled;
 
+// Set HTTP Cache type to be used by CronetEngine.  This method only has  any

[mef, 2017/01/18 22:39:51]

nit: remove extra space. Provide more elaborate comment, based on Java API:
https://cs.chromium.org/chromium/src/components/cronet/android/api/src/org/ch...

[lilyhoughton, 2017/01/19 16:17:15]

Done.

+// effect before |start| is called.
++ (void)setHttpCacheType:(HttpCacheType)http_cache;
+
 // 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;