[cronet] Expose API to set experimental options

components/cronet/ios/test/cronet_http_test.mm

Index: components/cronet/ios/test/cronet_http_test.mm
diff --git a/components/cronet/ios/test/cronet_http_test.mm b/components/cronet/ios/test/cronet_http_test.mm
index e1642feeaf9cbb5a6ad0cff8fdde7d7e7a03d6b1..fc392b6f9dbd2f74329c087168c8ee451ef73197 100644
--- a/components/cronet/ios/test/cronet_http_test.mm
+++ b/components/cronet/ios/test/cronet_http_test.mm
@@ -163,6 +163,17 @@ class HttpTest : public ::testing::Test {
   base::scoped_nsobject<TestDelegate> delegate_;
 };
 
+TEST(SslTest, CreateFile) {

[xunjieli, 2017/04/04 16:36:39]

I think this needs to be a TEST_F(HttpTest, CreateFile) in order for the
SetUp()/StartCronetIfNecessary() to be run. 

This test seems to be broken on the ios-simulator-cronet trybot.

https://luci-logdog.appspot.com/v/?s=chromium%2Fbb%2Ftryserver.chromium.mac%2...

+  bool ssl_file_created = [[NSFileManager defaultManager]
+      fileExistsAtPath:[Cronet getNetLogPathForFile:@"SSLKEYLOGFILE"]];
+
+  [[NSFileManager defaultManager]
+      removeItemAtPath:[Cronet getNetLogPathForFile:@"SSLKEYLOGFILE"]
+                 error:nil];
+
+  EXPECT_TRUE(ssl_file_created);
+}
+
 TEST_F(HttpTest, NSURLSessionReceivesData) {
   NSURL* url = net::NSURLWithGURL(GURL(grpc_support::kTestServerUrl));
   __block BOOL block_used = NO;