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

components/cronet/ios/Cronet.mm

Index: components/cronet/ios/Cronet.mm
diff --git a/components/cronet/ios/Cronet.mm b/components/cronet/ios/Cronet.mm
index 09b3c53b60f21dd13b510ea559f75abd1f0ecb15..19ecd0d76ea88a55911cc779064fdc53df78df63 100644
--- a/components/cronet/ios/Cronet.mm
+++ b/components/cronet/ios/Cronet.mm
@@ -33,6 +33,7 @@ base::LazyInstance<std::unique_ptr<cronet::CronetEnvironment>>::Leaky
 
 BOOL gHttp2Enabled = YES;
 BOOL gQuicEnabled = NO;
+HttpCacheType gHttpCache = HttpCacheType::DISK;
 ScopedVector<cronet::URLRequestContextConfig::QuicHint> gQuicHints;
 NSString* gUserAgent = nil;
 BOOL gUserAgentPartial = NO;
@@ -159,6 +160,11 @@ class CronetHttpProtocolHandlerDelegate
   gSslKeyLogFileName = sslKeyLogFileName;
 }
 
++ (void)setHttpCacheType:(HttpCacheType)httpCache {
+  [self checkNotStarted];
+  gHttpCache = httpCache;

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

I think this is a good place to map from ObjC to HttpCacheType.

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

Done; there may be a more robust way to map the ObjC enum to the C++ one, by
giving the enumerations explicit int values, so that this can be a simple cast
instead of a switch statement?

I don't know which would be clearest/easiest to maintain, though.

+}
+
 + (void)setRequestFilterBlock:(RequestFilterBlock)block {
   if (gHttpProtocolHandlerDelegate.get())
     gHttpProtocolHandlerDelegate.get()->SetRequestFilterBlock(block);
@@ -176,6 +182,7 @@ class CronetHttpProtocolHandlerDelegate
 
   gChromeNet.Get()->set_http2_enabled(gHttp2Enabled);
   gChromeNet.Get()->set_quic_enabled(gQuicEnabled);
+  gChromeNet.Get()->set_http_cache(gHttpCache);
   gChromeNet.Get()->set_ssl_key_log_file_name(
       base::SysNSStringToUTF8(gSslKeyLogFileName));
   for (const auto* quicHint : gQuicHints) {