Pepper: Log in UMA when an interface is used.

ppapi/tools/pepper_hash_for_uma.cc

Index: ppapi/tools/pepper_hash_for_uma.cc
diff --git a/ppapi/tools/pepper_hash_for_uma.cc b/ppapi/tools/pepper_hash_for_uma.cc
new file mode 100644
index 0000000000000000000000000000000000000000..705968e8820a00f2da29e2119679ccd910f02250
--- /dev/null
+++ b/ppapi/tools/pepper_hash_for_uma.cc
@@ -0,0 +1,31 @@
+// Copyright (c) 2014 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.
+//
+// This is a utility executable used for generating hashes for pepper
+// interfaces for inclusion in tools/metrics/histograms/histograms.xml. Every
+// interface-version pair must have a corresponding entry in the enum there.
+//
+// The hashing logic here must match the hashing logic at
+// ppapi/proxy/interface_list.cc.
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+#include "base/hash.h"
+#include "base/macros.h"
+
+int main(int argc, char **argv) {
+  if (argc != 2) {
+    fprintf(stderr, "Usage: %s <interface_name>", argv[0]);
+    return 1;
+  }
+  uint32 data = base::Hash(argv[1], strlen(argv[1]));
+
+  // Strip off the signed bit because UMA doesn't support negative values,
+  // but takes a signed int as input.
+  int hash = static_cast<int>(data & 0x7fffffff);
+  printf("%s: %d\n", argv[1], hash);
+  return 0;
+}