[Cronet] Make delaying sending request headers explicit in bidirectional stream

components/cronet/android/api/src/org/chromium/net/CronetEngine.java

Index: components/cronet/android/api/src/org/chromium/net/CronetEngine.java
diff --git a/components/cronet/android/api/src/org/chromium/net/CronetEngine.java b/components/cronet/android/api/src/org/chromium/net/CronetEngine.java
index 9dbcc5a091559ff6524d45d7cb8349748f9c3ef6..e4ae854a53569298bc286ee0dfce912694e4f680 100644
--- a/components/cronet/android/api/src/org/chromium/net/CronetEngine.java
+++ b/components/cronet/android/api/src/org/chromium/net/CronetEngine.java
@@ -711,12 +711,16 @@ public abstract class CronetEngine {
      *         {@link BidirectionalStream.Builder#STREAM_PRIORITY_IDLE STREAM_PRIORITY_*}
      *         values.
      * @param disableAutoFlush whether auto flush should be disabled
+     * @param delayRequestHeadersUntilFirstFlush whether to delay sending request
+     *         headers until flush() is called, and try to combine them
+     *         with the next data frame.
      * @return a new stream.
      */
     abstract BidirectionalStream createBidirectionalStream(String url,
             BidirectionalStream.Callback callback, Executor executor, String httpMethod,
             List<Map.Entry<String, String>> requestHeaders,
-            @BidirectionalStream.Builder.StreamPriority int priority, boolean disableAutoFlush);
+            @BidirectionalStream.Builder.StreamPriority int priority, boolean disableAutoFlush,
+            boolean delayRequestHeadersUntilFirstFlush);
 
     /**
      * @return {@code true} if the engine is enabled.