Added OverwriteFlags method to SpdyFrameBuilder.

net/spdy/spdy_frame_builder.h

Index: net/spdy/spdy_frame_builder.h
diff --git a/net/spdy/spdy_frame_builder.h b/net/spdy/spdy_frame_builder.h
index 9e26cccd1b5b09f3559828990d569cfd175361f6..f9826d0ae5301ecea8292534b734be21d41227d0 100644
--- a/net/spdy/spdy_frame_builder.h
+++ b/net/spdy/spdy_frame_builder.h
@@ -117,6 +117,11 @@ class NET_EXPORT_PRIVATE SpdyFrameBuilder {
   // with the correct version for the frame being written.
   bool OverwriteLength(const SpdyFramer& framer, size_t length);
 
+  // Update (in-place) the flags field in the frame being built to reflect the
+  // given flags value.
+  // Used only for SPDY versions >=4.
+  bool OverwriteFlags(const SpdyFramer& framer, uint8 flags);
+
  private:
   // Checks to make sure that there is an appropriate amount of space for a
   // write of given size, in bytes.