Pepper: Log in UMA when an interface is used.

We'd like to know what versions of our interfaces are used by end users. This
change logs usage of PPB interfaces for out-of-process plugins the first time
that get_interface<>() is called for a given interface and version.

I tested this change by loading some plugin examples and checking the
about:histograms page.

BUG=111542
R=asvitkine@chromium.org, jschuh@chromium.org, yzshen@chromium.org

Review URL: https://codereview.chromium.org/141523010

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@249007 0039d316-1c4b-4281-b951-d872f2087c98

2 files changed, 49 insertions, 0 deletions

diff --git a/ppapi/tools/pepper_hash_for_uma.cc b/ppapi/tools/pepper_hash_for_uma.cc
new file mode 100644
index 0000000..705968e
--- /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;
+}
diff --git a/ppapi/tools/ppapi_tools.gyp b/ppapi/tools/ppapi_tools.gyp
new file mode 100644
index 0000000..67986ff
--- /dev/null
+++ b/ppapi/tools/ppapi_tools.gyp
@@ -0,0 +1,18 @@
+# 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.
+
+{
+  'targets': [
+    {
+      'target_name': 'pepper_hash_for_uma',
+      'type': 'executable',
+      'dependencies': [
+        '../../base/base.gyp:base'
+      ],
+      'sources': [
+        'pepper_hash_for_uma.cc',
+      ],
+    }
+  ]
+}