Adds a field trial to control Web API kill switches.

chrome/browser/permissions/permission_util.cc

+// Copyright 2015 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 "chrome/browser/permissions/permission_util.h"
+
+// The returned strings must match the RAPPOR metrics in rappor.xml,
+// and any Finch configs for the Permissions kill switch e.g.
+// Permissions.Action.Geolocation etc..

[mlamouri (slow - plz ping), 2015/10/21 11:26:06]

nit: it shouldn't match RAPPOR and Finch but the other way around. Maybe you
should remove this comment.

[kcarattini, 2015/10/26 00:30:59]

The comment was meant for people editing the code to be aware what metrics are
dependent on a certain string being returned. It probably makes sense to define
these somewhere else. I was thinking event that each PermissionContext subclass
could have its own "name" field or something,

+const std::string PermissionUtil::GetPermissionString(
+    ContentSettingsType permission) {
+  switch (permission) {
+    case CONTENT_SETTINGS_TYPE_GEOLOCATION:
+      return "Geolocation";
+    case CONTENT_SETTINGS_TYPE_NOTIFICATIONS:
+      return "Notifications";
+    case CONTENT_SETTINGS_TYPE_MIDI_SYSEX:
+      return "MidiSysEx";
+    case CONTENT_SETTINGS_TYPE_PUSH_MESSAGING:
+      return "PushMessaging";
+    case CONTENT_SETTINGS_TYPE_DURABLE_STORAGE:
+      return "DurableStorage";
+#if defined(OS_ANDROID) || defined(OS_CHROMEOS)
+    case CONTENT_SETTINGS_TYPE_PROTECTED_MEDIA_IDENTIFIER:
+      return "ProtectedMediaIdentifier";
+#endif
+    case CONTENT_SETTINGS_TYPE_MEDIASTREAM_MIC:
+      return "AudioCapture";
+    case CONTENT_SETTINGS_TYPE_MEDIASTREAM_CAMERA:
+      return "VideoCapture";
+    default:
+      NOTREACHED();
+      return "";

[Bernhard Bauer, 2015/10/21 10:29:04]

Use an empty std::string() constructor to save a couple of instructions.

[kcarattini, 2015/10/26 00:30:59]

Done.

+  }
+}