bluetooth: Create bluetooth_metrics_hash tool.

content/browser/bluetooth/tools/bluetooth_metrics_hash.cc

Index: content/browser/bluetooth/tools/bluetooth_metrics_hash.cc
diff --git a/content/browser/bluetooth/tools/bluetooth_metrics_hash.cc b/content/browser/bluetooth/tools/bluetooth_metrics_hash.cc
new file mode 100644
index 0000000000000000000000000000000000000000..f0c52dc6ce9ea60fcbc7dee50a7442f9dc8f4377
--- /dev/null
+++ b/content/browser/bluetooth/tools/bluetooth_metrics_hash.cc
@@ -0,0 +1,47 @@
+// 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 <iostream>
+
+#include "base/hash.h"
+#include "base/logging.h"
+#include "device/bluetooth/bluetooth_uuid.h"
+
+int main(int argc, char** argv) {
+  if (argc <= 1) {
+    std::cout << "Generates hash values given UUIDs using the same method\n"
+              << "as in bluetooth_metrics.cc.\n"
+              << "\n"
+              << "Output is formatted for including into histograms.xml.\n"
+              << "Note that tools/metrics/histograms/pretty_print.py will\n"
+              << "sort enum entries for you.\n"
+              << "\n"
+              << "Usage: " << argv[0] << " <uuid> [uuid2 ...]\n"
+              << "       The UUIDs may be short UUIDs, and will be made\n"
+              << "       canonical before being hashed.\n"
+              << "\n"
+              << "Example: " << argv[0] << " FEFF FEFE\n"
+              << "  <int value=\"62669585\" "
+                 "label=\"0000feff-0000-1000-8000-00805f9b34fb\"/>\n"
+              << "  <int value=\"643543662\" "
+                 "label=\"0000fefe-0000-1000-8000-00805f9b34fb\"/>\n";
+    return 1;
+  }
+
+  for (int i = 1; i < argc; i++) {
+    std::string input_string(argv[i]);
+    device::BluetoothUUID uuid(input_string);
+    std::string uuid_canonical_string = uuid.canonical_value();
+    uint32_t hash = base::SuperFastHash(uuid_canonical_string.data(),
+                                        uuid_canonical_string.size());
+
+    // Strip off the signed bit because UMA doesn't support negative values,

[Jeffrey Yasskin, 2016/04/15 21:23:58]

s/signed bit/sign bit/: https://en.wikipedia.org/wiki/Sign_bit

[scheib, 2016/04/15 22:45:22]

Done.

+    // but takes a signed int as input.
+    hash &= 0x7fffffff;
+
+    std::cout << "  <int value=\"" << hash << "\" label=\""
+              << uuid_canonical_string << "\"/>\n";
+  }
+  return 0;
+}