Added explicit EOR to sctp messages and coalesce messages on the receiving side.

TBR=pthatcher@webrtc.org

Bug: webrtc:7774
Change-Id: I41d1cd98d1e7b2ad479177eb2e328a5e2c704824
Reviewed-on: https://webrtc-review.googlesource.com/88900
Commit-Queue: Jeroen de Borst <jeroendb@webrtc.org>
Reviewed-by: Qingsi Wang <qingsi@webrtc.org>
Reviewed-by: Steve Anton <steveanton@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#24031}
diff --git a/rtc_base/copyonwritebuffer.h b/rtc_base/copyonwritebuffer.h
index 467baad..0514e2f 100644
--- a/rtc_base/copyonwritebuffer.h
+++ b/rtc_base/copyonwritebuffer.h
@@ -31,6 +31,9 @@
   // Move contents from an existing buffer.
   CopyOnWriteBuffer(CopyOnWriteBuffer&& buf);
 
+  // Construct a buffer from a string, convenient for unittests.
+  CopyOnWriteBuffer(const std::string& s);
+
   // Construct a buffer with the specified number of uninitialized bytes.
   explicit CopyOnWriteBuffer(size_t size);
   CopyOnWriteBuffer(size_t size, size_t capacity);