Add new HTTP/2 and HPACK decoder in net/http2/.

net/http2/hpack/tools/hpack_example.cc

Index: net/http2/hpack/tools/hpack_example.cc
diff --git a/net/http2/hpack/tools/hpack_example.cc b/net/http2/hpack/tools/hpack_example.cc
new file mode 100644
index 0000000000000000000000000000000000000000..72fd5810e991d0ef563e9c64cf2d3c9265a97489
--- /dev/null
+++ b/net/http2/hpack/tools/hpack_example.cc
@@ -0,0 +1,61 @@
+// Copyright 2016 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "net/http2/hpack/tools/hpack_example.h"
+
+#include <ctype.h>
+
+#include "base/logging.h"
+#include "net/spdy/spdy_test_utils.h"
+
+using base::StringPiece;
+using std::string;
+
+namespace net {
+namespace test {
+namespace {
+
+void HpackExampleToStringOrDie(StringPiece example, string* output) {
+  while (!example.empty()) {
+    const char c0 = example[0];
+    if (isxdigit(c0)) {
+      CHECK_GT(example.size(), 1u) << "Truncated hex byte?";
+      const char c1 = example[1];
+      CHECK(isxdigit(c1)) << "Found half a byte?";
+      *output += a2b_hex(example.substr(0, 2).as_string().c_str());
+      example.remove_prefix(2);
+      continue;
+    }
+    if (isspace(c0)) {
+      example.remove_prefix(1);
+      continue;
+    }
+    if (example.starts_with("|")) {
+      // Start of a comment. Skip to end of line or of input.
+      auto pos = example.find('\n');
+      if (pos == StringPiece::npos) {
+        // End of input.
+        break;
+      }
+      example.remove_prefix(pos + 1);
+      continue;
+    }
+    CHECK(false) << "Can't parse byte " << static_cast<int>(c0) << " (0x"
+                 << std::hex << c0 << ")"
+                 << "\nExample: " << example;
+  }
+  CHECK_LT(0u, output->size()) << "Example is empty.";
+  return;
+}
+
+}  // namespace
+
+string HpackExampleToStringOrDie(StringPiece example) {
+  string output;
+  HpackExampleToStringOrDie(example, &output);
+  return output;
+}
+
+}  // namespace test
+}  // namespace net