Initial implementation of CronetBidirectionalStream.

components/cronet/android/java/src/org/chromium/net/CronetUrlRequestContext.java

Index: components/cronet/android/java/src/org/chromium/net/CronetUrlRequestContext.java
diff --git a/components/cronet/android/java/src/org/chromium/net/CronetUrlRequestContext.java b/components/cronet/android/java/src/org/chromium/net/CronetUrlRequestContext.java
index 227bd41f9d8c4c389f99e220bfc1e45b54d049fc..df43dc12c60764b0ab4b60b884490012434b8c9e 100644
--- a/components/cronet/android/java/src/org/chromium/net/CronetUrlRequestContext.java
+++ b/components/cronet/android/java/src/org/chromium/net/CronetUrlRequestContext.java
@@ -120,7 +120,11 @@ class CronetUrlRequestContext extends CronetEngine {
     @Override
     BidirectionalStream createBidirectionalStream(String url, BidirectionalStream.Callback callback,
             Executor executor, String httpMethod, List<Map.Entry<String, String>> requestHeaders) {
-        throw new UnsupportedOperationException();
+        synchronized (mLock) {
+            checkHaveAdapter();
+            return new CronetBidirectionalStream(this, mUrlRequestContextAdapter, url, callback,
+                    executor, httpMethod, requestHeaders);
+        }
     }
 
     @Override
@@ -300,7 +304,7 @@ class CronetUrlRequestContext extends CronetEngine {
      * Mark request as started to prevent shutdown when there are active
      * requests.
      */
-    void onRequestStarted(UrlRequest urlRequest) {
+    void onRequestStarted() {
         mActiveRequestCount.incrementAndGet();
     }
 
@@ -308,7 +312,7 @@ class CronetUrlRequestContext extends CronetEngine {
      * Mark request as completed to allow shutdown when there are no active
      * requests.
      */
-    void onRequestDestroyed(UrlRequest urlRequest) {
+    void onRequestDestroyed() {
         mActiveRequestCount.decrementAndGet();
     }