[Cronet] Coalesce small buffers into single QUIC packet in GRPC on iOS.

components/cronet/ios/cronet_c_for_grpc.h

Index: components/cronet/ios/cronet_c_for_grpc.h
diff --git a/components/cronet/ios/cronet_c_for_grpc.h b/components/cronet/ios/cronet_c_for_grpc.h
index 187cde78de93a816b277aaf38f60205971d2645e..9e7a8ad21137dcc1d56b1ae33ea75c68941bd182 100644
--- a/components/cronet/ios/cronet_c_for_grpc.h
+++ b/components/cronet/ios/cronet_c_for_grpc.h
@@ -144,6 +144,27 @@ cronet_bidirectional_stream* cronet_bidirectional_stream_create(
 CRONET_EXPORT
 int cronet_bidirectional_stream_destroy(cronet_bidirectional_stream* stream);
 
+/**
+ * Disables or enables auto flush. By default, data is flushed after
+ * every cronet_bidirectional_stream_write(). If the auto flush is disabled,
+ * the client should explicitly call cronet_bidirectional_stream_flush to flush
+ * the data.
+ */
+CRONET_EXPORT int cronet_bidirectional_stream_disable_auto_flush(
+    cronet_bidirectional_stream* stream,
+    bool disable_auto_flush);
+
+/**
+ * Delays sending request headers until cronet_bidirectional_stream_flush()
+ * is called. This flag is currently only respected when QUIC is negotiated.
+ * When true, QUIC will send request header frame along with data frame(s)
+ * as a single packet when possible.
+ */
+CRONET_EXPORT
+int cronet_bidirectional_stream_delay_request_headers_until_flush(
+    cronet_bidirectional_stream* stream,
+    bool delay_headers_until_flush);
+
 /* Start the stream by sending request to |url| using |method| and |headers|. If
  * |end_of_stream| is true, then no data is expected to be written. The |method|
  * is HTTP verb, with PUT having a special meaning to mark idempotent request,
@@ -172,10 +193,9 @@ int cronet_bidirectional_stream_read(cronet_bidirectional_stream* stream,
                                      char* buffer,
                                      int capacity);
 
-/* Write request data from |buffer| of |buffer_length| length. Must only be
- * called at most once in response to each invocation of the
- * on_stream_ready() and on_write_completed() methods of the
- * cronet_bidirectional_stream_callback.
+/* Write request data from |buffer| of |buffer_length| length. If auto flush is

[xunjieli, 2016/06/10 16:30:50]

nit: Writes?

[mef, 2016/06/10 18:36:37]

Done.

+ * disabled, data will be sent only after cronet_bidirectional_stream_flush() is
+ * called.
  * Each call will result in an invocation the callback's on_write_completed()
  * method if data is sent, or its on_failed() method if there's an error.
  * The callback's on_succeeded() method is also invoked if |end_of_stream| is
@@ -187,6 +207,16 @@ int cronet_bidirectional_stream_write(cronet_bidirectional_stream* stream,
                                       int buffer_length,
                                       bool end_of_stream);
 
+/**
+ * Flush pending writes. This method should not be called before invocation of

[xunjieli, 2016/06/10 16:30:50]

nit: Flushes?

[mef, 2016/06/10 18:36:37]

Done.

+ * on_stream_ready() method of the cronet_bidirectional_stream_callback.
+ * For each previously called cronet_bidirectional_stream_write()
+ * a corresponding on_write_completed() callback will be invoked when the buffer
+ * is sent.
+ */
+CRONET_EXPORT
+int cronet_bidirectional_stream_flush(cronet_bidirectional_stream* stream);
+
 /* Cancels the stream. Can be called at any time after
  * cronet_bidirectional_stream_start(). The on_canceled() method of
  * cronet_bidirectional_stream_callback will be invoked when cancelation