Refactor the various ways to control what users can do to extensions.

chrome/browser/extensions/management_policy.cc

+// Copyright (c) 2012 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/extensions/management_policy.h"
+
+namespace extensions {
+ManagementPolicy::ManagementPolicy() {
+}
+
+ManagementPolicy::~ManagementPolicy() {
+}
+
+bool ManagementPolicy::Provider::UserMayLoad(const Extension* extension,
+                                             Extension::Location location,
+                                             string16* error) const {
+  return true;
+}
+
+bool ManagementPolicy::Provider::UserMayModifyStatus(const Extension* extension,
+                                                     string16* error) const {
+  return true;
+}
+
+bool ManagementPolicy::Provider::MustRemainEnabled(const Extension* extension,
+                                                   string16* error) const {
+  return false;
+}
+
+void ManagementPolicy::RegisterProvider(Provider* provider) {
+  providers_.insert(provider);
+}
+
+void ManagementPolicy::UnregisterProvider(Provider* provider) {
+  providers_.erase(provider);
+}
+
+bool ManagementPolicy::UserMayLoad(const Extension* extension,
+                                   Extension::Location location,
+                                   string16* error) const {

[Aaron Boodman, 2012/05/22 15:56:11]

Seems like the logic from Extension::IsRequired() could move here.

+  for (ProviderList::const_iterator it = providers_.begin();
+      it != providers_.end(); ++it) {
+    if (!(*it)->UserMayLoad(extension, location, error)) {
+      // The extension may be NULL in testing.
+      std::string id = extension ? extension->id() : "[test]";
+      DLOG(WARNING) << "Installation of extension " << id
+                    << " prohibited by " << (*it)->PolicyProviderName();

[Pam (message me for reviews), 2012/05/22 12:51:07]

Sure. To avoid spam, since these get called to check whether to show UI and so
on too, I'll make it a warning.
Yes, as long as we also pass the location, since CrxInstaller doesn't save that
to the extension until it's successful. Done.

+      return false;
+    }
+  }
+  return true;
+}
+
+bool ManagementPolicy::UserMayModifyStatus(const Extension* extension,
+                                           string16* error) const {
+  for (ProviderList::const_iterator it = providers_.begin();
+      it != providers_.end(); ++it) {
+    if (!(*it)->UserMayModifyStatus(extension, error)) {
+      // The extension may be NULL in testing.
+      std::string id = extension ? extension->id() : "[test]";
+      DLOG(WARNING) << "Modification of extension " << id
+                    << " prohibited by " << (*it)->PolicyProviderName();
+      return false;
+    }
+  }
+  return true;
+}
+
+bool ManagementPolicy::MustRemainEnabled(const Extension* extension,
+                                         string16* error) const {
+  for (ProviderList::const_iterator it = providers_.begin();
+      it != providers_.end(); ++it) {
+      // The extension may be NULL in testing.
+      std::string id = extension ? extension->id() : "[test]";
+      if ((*it)->MustRemainEnabled(extension, error)) {
+      DLOG(WARNING) << "Extension " << id
+                    << " required to remain enabled by "
+                    << (*it)->PolicyProviderName();
+      return true;
+    }
+  }
+  return false;
+}
+
+void ManagementPolicy::UnregisterAllProviders() {
+  providers_.clear();
+}
+
+int ManagementPolicy::GetNumProviders() const {
+  return providers_.size();
+}
+}  // namespace