Moving gRPC support interfaces out of cronet and into a new component.

components/cronet/ios/test/start_cronet.mm

+// 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 <Cronet/Cronet.h>
+#import <Foundation/Foundation.h>
+
+#include "components/cronet/ios/test/start_cronet.h"
+
+#include "base/at_exit.h"
+#include "components/grpc_support/test/quic_test_server.h"
+
+namespace cronet {
+
+base::AtExitManager* g_at_exit_ = nullptr;
+
+void StartCronetIfNecessary() {
+  static bool initialized = false;
+  if (!initialized) {
+    initialized = true;
+    [Cronet setUserAgent:@"CronetTest/1.0.0.0" partial:NO];
+    [Cronet setHttp2Enabled:true];
+    [Cronet setQuicEnabled:true];
+    [Cronet setSslKeyLogFileName:@"SSLKEYLOGFILE"];
+    [Cronet addQuicHint:@"test.example.com"
+                   port:grpc_support::kTestServerPort
+                altPort:grpc_support::kTestServerPort];
+    [Cronet enableTestCertVerifierForTesting];
+    [Cronet
+        setHostResolverRulesForTesting:@"MAP test.example.com 127.0.0.1,"
+                                        "MAP notfound.example.com ~NOTFOUND"];
+    [Cronet start];
+
+    // This method must be called once from the main thread.
+    if (!g_at_exit_)
+      g_at_exit_ = new base::AtExitManager;
+  }
+}
+
+}  // namespace cronet