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..52f81d9f348b124dadb47e6dff4b12cc59ea5830 100644
--- a/components/cronet/ios/Cronet.h
+++ b/components/cronet/ios/Cronet.h
@@ -10,6 +10,17 @@
 // 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);
@@ -28,6 +39,11 @@ 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
+// 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;