Split net/spdy into core and chromium subdirectories.

Create net/spdy/core for files (and subdirectories: hpack and fuzzer)
that are shared with internal code.  Create net/spdy/chromium for
Chromium-specific source files.  Leave platform and OWNERS at net/spdy
level.

This follows the pattern established in net/quic, and is going to make
it possible to have presubmit checks for net/spdy/core that make it
easier to maintain shared code.

CQ_INCLUDE_TRYBOTS=master.tryserver.chromium.android:android_cronet_tester

Review-Url: https://codereview.chromium.org/2832973003
Cr-Commit-Position: refs/heads/master@{#466681}
diff --git a/net/quic/test_tools/quic_test_utils.cc b/net/quic/test_tools/quic_test_utils.cc
index 63eb3c9..930fd26 100644
--- a/net/quic/test_tools/quic_test_utils.cc
+++ b/net/quic/test_tools/quic_test_utils.cc
@@ -23,7 +23,7 @@
 #include "net/quic/platform/api/quic_ptr_util.h"
 #include "net/quic/test_tools/crypto_test_utils.h"
 #include "net/quic/test_tools/quic_connection_peer.h"
-#include "net/spdy/spdy_frame_builder.h"
+#include "net/spdy/core/spdy_frame_builder.h"
 #include "third_party/boringssl/src/include/openssl/sha.h"
 
 using std::string;