Log source_dependency in HTTP2_SESSION_SEND_HEADERS.

net/spdy/spdy_session_pool_unittest.cc

Index: net/spdy/spdy_session_pool_unittest.cc
diff --git a/net/spdy/spdy_session_pool_unittest.cc b/net/spdy/spdy_session_pool_unittest.cc
index 2d0d845e9f9a8179ed20ddd85f6d152a31320bfb..dbdade06cfe3eaf28ffd2e1f56bbb1abc8feaf12 100644
--- a/net/spdy/spdy_session_pool_unittest.cc
+++ b/net/spdy/spdy_session_pool_unittest.cc
@@ -93,6 +93,8 @@ class SessionOpeningDelegate : public SpdyStream::Delegate {
     ignore_result(CreateFakeSpdySession(spdy_session_pool_, key_));
   }
 
+  NetLogSource source_dependency() const override { return NetLogSource(); }
+
  private:
   SpdySessionPool* const spdy_session_pool_;
   const SpdySessionKey key_;