Add migration code for the EnabledPlugins and DisabledPlugins policies.

chrome/browser/plugins/plugin_policy_handler.h

+// Copyright (c) 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.
+
+#ifndef CHROME_BROWSER_PLUGINS_PLUGIN_POLICY_HANDLER_H_
+#define CHROME_BROWSER_PLUGINS_PLUGIN_POLICY_HANDLER_H_
+
+#include <map>
+#include <set>
+#include <vector>
+
+#include "base/macros.h"
+#include "chrome/browser/plugins/plugin_prefs.h"
+#include "components/content_settings/core/common/content_settings.h"
+#include "components/policy/core/browser/configuration_policy_handler.h"
+#include "components/policy/policy_constants.h"
+#include "components/prefs/pref_value_map.h"
+
+// Migrates values of deprecated plugin policies into their new counterpars.
+// It reads the set of EnabledPlugins and DisabledPlugins and updates the Flash
+// default behavior and PDF plugin behavior. All other values in the list are
+// ignored. The string matching rules are not trying to catch edge cases like
+// matching "Shockwave Flash Player" by "????????*Player". Only the direct
+// mentioning of "PDF" and "FLASH" or the wildcard "*" element are migrated to
+// the new policies.

[Bernhard Bauer, 2016/10/12 15:28:49]

Hm... wouldn't it actually be _easier_ to just match the pattern defined by
policy against, say, "Shockwave Flash Player" and "PDF Viewer"? I get the
feeling that would miss fewer edge cases, and be slightly less code as well.

[pastarmovj, 2016/10/13 13:29:00]

We have been advising admins on various bugs to be broader in the old NPAPI days
and use the wildcard specs to catch all version of particular plugins so I think
it is expected that there is a fair number of wildcard policies out in the wild.

[Bernhard Bauer, 2016/10/13 14:33:08]

I don't doubt there are wildcard policies out in the wild (heh), but it appears
to me the easiest way to check whether a given pattern is meant to match e.g.
Flash would be... to match it against Flash, no? (Where "match" here means using
the pattern semantics that we have defined in the policy.)

+class PluginPolicyHandler : public policy::ConfigurationPolicyHandler {
+ public:
+  PluginPolicyHandler();
+  ~PluginPolicyHandler() override;
+
+ protected:
+  bool CheckPolicySettings(const policy::PolicyMap& policies,
+                           policy::PolicyErrorMap* errors) override;
+  void ApplyPolicySettings(const policy::PolicyMap& policies,
+                           PrefValueMap* prefs) override;
+
+ private:
+  void ProcessPolicy(const policy::PolicyMap& policies,
+                     PrefValueMap* prefs,
+                     const std::string& policy,
+                     bool disable_pdf_plugin,
+                     ContentSetting flash_content_setting);
+
+  DISALLOW_COPY_AND_ASSIGN(PluginPolicyHandler);
+};
+
+#endif  // CHROME_BROWSER_PLUGINS_PLUGIN_POLICY_HANDLER_H_