[SafeBrowsing] Block dangerous unchecked downloads based on a Finch trial.

chrome/browser/safe_browsing/unverified_download_field_trial.h

+// 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.
+
+#ifndef CHROME_BROWSER_SAFE_BROWSING_UNVERIFIED_DOWNLOAD_FIELD_TRIAL_H_
+#define CHROME_BROWSER_SAFE_BROWSING_UNVERIFIED_DOWNLOAD_FIELD_TRIAL_H_
+
+namespace base {
+class FilePath;
+}
+
+namespace safe_browsing {
+
+// Unverified Download Field Trial
+//
+// It is possible in some circumstances to download a file without invoking
+// SafeBrowsing to verify the source URLs or the downloaded contents. Ideally
+// all code paths that writes untrusted contents to disk in a user discoverable
+// manner would invoke SafeBrowsing. But until all such code paths are properly
+// plumbed, this field trial will help control the behavior of known unverified
+// code paths.
+
+extern const char kUnverifiedDownloadFieldTrialName[];
+
+// The trial groups are:
+//
+// * DisableAll : Disables all unverified downloads regardless of whether the
+//     specific file in question is potentially dangerous or handled by Safe
+//     Browsing at all.
+extern const char kUnverifiedDownloadFieldTrialDisableAll[];
+
+// * DisableByParameter : Decides the fate of unverified downloads based on
+//     whether the file type matches a whitelist and a blacklist specified as a
+//     parameter to this trial group. Any file type that doesn't match either of
+//     these lists will default to being allowed.
+extern const char kUnverifiedDownloadFieldTrialDisableByParameter[];
+
+//     The parameters are:
+//
+//     - 'whitelist' : A comma separated list of file types including leading
+//         extension separator. E.g. ".abc,.def" would match both foo.abc and
+//         foo.def, but not foo.txt. Any matching file will be allowed to be
+//         downloaded.
+extern const char kUnverifiedDownloadFieldTrialWhitelistParam[];
+
+//     - 'blacklist' : Similar in format to 'whitelist' but causes matching file
+//         types to be disallowed from downloading.
+extern const char kUnverifiedDownloadFieldTrialBlacklistParam[];
+
+// * DisableSBTypesAndByParameter : Applies the whitelist and blacklist as
+//     described in DisableByParameter. However, any file type that doesn't
+//     match either list but is considered supported by SafeBrowsing will be
+//     blocked.
+extern const char kUnverifiedDownloadFieldTrialDisableSBTypesAndByParameter[];
+
+// Returns true if |file| is allowed to be downloaded based on the current field
+// trial settings.
+bool IsUnverifiedDownloadAllowedByFieldTrial(const base::FilePath& file);
+
+}  // namespace safe_browsing
+
+#endif  // CHROME_BROWSER_SAFE_BROWSING_UNVERIFIED_DOWNLOAD_FIELD_TRIAL_H_