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

components/cronet/android/cronet_url_request_context_adapter.h

Index: components/cronet/android/cronet_url_request_context_adapter.h
diff --git a/components/cronet/android/cronet_url_request_context_adapter.h b/components/cronet/android/cronet_url_request_context_adapter.h
index 664c8f39689fc10a974aafd5083c91cb26c7b420..b9a4796acbb3a1c83a27f0770b8c63eccd6a266f 100644
--- a/components/cronet/android/cronet_url_request_context_adapter.h
+++ b/components/cronet/android/cronet_url_request_context_adapter.h
@@ -62,8 +62,8 @@ class CronetURLRequestContextAdapter
 
   ~CronetURLRequestContextAdapter() override;
 
-  // Called on main Java thread to initialize URLRequestContext.
-  void InitRequestContextOnMainThread(
+  // Called on init Java thread to initialize URLRequestContext.
+  void InitRequestContextOnInitThread(
       JNIEnv* env,
       const base::android::JavaParamRef<jobject>& jcaller);
 
@@ -111,8 +111,8 @@ class CronetURLRequestContextAdapter
   // Default net::LOAD flags used to create requests.
   int default_load_flags() const { return default_load_flags_; }
 
-  // Called on main Java thread to initialize URLRequestContext.
-  void InitRequestContextOnMainThread();
+  // Called on init Java thread to initialize URLRequestContext.
+  void InitRequestContextOnInitThread();
 
   // Configures the network quality estimator to observe requests to localhost,
   // to use smaller responses when estimating throughput, and to disable the