Added HttpUrlRequestListener OnResponseStarted callback.

BUG=354143

Review URL: https://codereview.chromium.org/258073003

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@266741 0039d316-1c4b-4281-b951-d872f2087c98

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

@@ -112,6 +112,7 @@ class ChromiumUrlRequest extends UrlRequest implements HttpUrlRequest {
                 mSize = mOffset;
             }
         }
+        mListener.onResponseStarted(this);
     }
 
     @Override

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

@@ -8,6 +8,12 @@ package org.chromium.net;
  * Callback interface.
  */
 public interface HttpUrlRequestListener {
+    /**
+     * A callback invoked when the first chunk of the response has arrived.
+     * The listener can only call request getContentType and getContentLength.
+     */
+    void onResponseStarted(HttpUrlRequest request);
+
     /**
      * The listener should completely process the response in the callback
      * method. Immediately after the callback, the request object will be

components/cronet/android/sample/src/org/chromium/cronet_sample_apk/CronetSampleActivity.java

@@ -89,6 +89,12 @@ public class CronetSampleActivity extends Activity {
         public SampleHttpUrlRequestListener() {
         }
 
+        @Override
+        public void onResponseStarted(HttpUrlRequest request) {
+            Log.i(TAG, "****** Response Started, content length is "
+                    + request.getContentLength());
+        }
+
         @Override
         public void onRequestComplete(HttpUrlRequest request) {
             Log.i(TAG, "****** Request Complete, status code is "