[Cronet] Move initialization to a new thread rather than the UI thread.

components/cronet/android/cronet_library_loader.cc

 // Copyright 2014 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.
 
 #include "components/cronet/android/cronet_library_loader.h"
 
 #include <jni.h>
 #include <vector>
 
 #include "base/android/base_jni_onload.h"
@@ skipping 34 matching lines @@
     {"CronetBidirectionalStreamAdapter",
      CronetBidirectionalStreamAdapter::RegisterJni},
     {"CronetLibraryLoader", RegisterNativesImpl},
     {"CronetUploadDataStreamAdapter", CronetUploadDataStreamAdapterRegisterJni},
     {"CronetUrlRequestAdapter", CronetUrlRequestAdapterRegisterJni},
     {"CronetUrlRequestContextAdapter",
      CronetUrlRequestContextAdapterRegisterJni},
     {"NetAndroid", net::android::RegisterJni},
 };
 
-// MessageLoop on the main thread, which is where objects that receive Java
+// MessageLoop on the init thread, which is where objects that receive Java
 // notifications generally live.
-base::MessageLoop* g_main_message_loop = nullptr;
+base::MessageLoop* g_init_message_loop = nullptr;
 
 net::NetworkChangeNotifier* g_network_change_notifier = nullptr;
 
 bool RegisterJNI(JNIEnv* env) {
   return base::android::RegisterNativeMethods(
       env, kCronetRegisteredMethods, arraysize(kCronetRegisteredMethods));
 }
 
 bool NativeInit() {
   if (!base::android::OnJNIOnLoadInit())
     return false;
   url::Initialize();
   return true;
 }
 
 }  // namespace
 
+bool OnInitThread() {

[xunjieli, 2017/04/13 18:44:54]

This global static function will return true if g_init_message_loop and
base::MessageLoop::current() are both not initialized.

Can you add a comment on when this function can be called? Alternatively could
add a check on |g_init_message_loop != nullptr|

[pauljensen, 2017/05/01 15:35:53]

Done.

+  return g_init_message_loop == base::MessageLoop::current();
+}
+
 // Checks the available version of JNI. Also, caches Java reflection artifacts.
 jint CronetOnLoad(JavaVM* vm, void* reserved) {
   base::android::InitVM(vm);
   JNIEnv* env = base::android::AttachCurrentThread();
   if (!base::android::OnJNIOnLoadRegisterJNI(env) || !RegisterJNI(env) ||
       !NativeInit()) {
     return -1;
   }
   return JNI_VERSION_1_6;
 }
 
 void CronetOnUnLoad(JavaVM* jvm, void* reserved) {
   base::android::LibraryLoaderExitHook();
 }
 
-void CronetInitOnMainThread(JNIEnv* env, const JavaParamRef<jclass>& jcaller) {
+void CronetInitOnInitThread(JNIEnv* env, const JavaParamRef<jclass>& jcaller) {
 #if !BUILDFLAG(USE_PLATFORM_ICU_ALTERNATIVES)
   base::i18n::InitializeICU();
 #endif
 
   base::FeatureList::InitializeInstance(std::string(), std::string());
   // TODO(bengr): Remove once Data Reduction Proxy no longer needs this for
   // configuration information.
   base::CommandLine::Init(0, nullptr);
   DCHECK(!base::MessageLoop::current());
-  DCHECK(!g_main_message_loop);
-  g_main_message_loop = new base::MessageLoopForUI();
-  base::MessageLoopForUI::current()->Start();
+  DCHECK(!g_init_message_loop);
+  g_init_message_loop = new base::MessageLoop();
   DCHECK(!g_network_change_notifier);
   net::NetworkChangeNotifier::SetFactory(
       new net::NetworkChangeNotifierFactoryAndroid());
   g_network_change_notifier = net::NetworkChangeNotifier::Create();
 }
 
 ScopedJavaLocalRef<jstring> GetCronetVersion(
     JNIEnv* env,
     const JavaParamRef<jclass>& jcaller) {
   return base::android::ConvertUTF8ToJavaString(env, CRONET_VERSION);
 }
 
 }  // namespace cronet