Start refractoring extension permissions into ExtensionPermissionSet.

chrome/common/extensions/extension_permission_set.cc

+// Copyright (c) 2011 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/common/extensions/extension_permission_set.h"
+
+#include <algorithm>
+#include <string>
+
+#include "base/memory/singleton.h"
+#include "base/values.h"
+#include "base/string_number_conversions.h"
+#include "base/utf_string_conversions.h"
+#include "chrome/common/extensions/extension.h"
+#include "chrome/common/extensions/extension_constants.h"
+#include "chrome/common/extensions/extension_l10n_util.h"
+#include "chrome/common/extensions/url_pattern.h"
+#include "chrome/common/extensions/url_pattern_set.h"
+#include "grit/generated_resources.h"
+#include "net/base/registry_controlled_domain.h"
+#include "ui/base/l10n/l10n_util.h"
+
+namespace {
+
+// Helper for GetDistinctHosts(): com > net > org > everything else.
+bool RcdBetterThan(std::string a, std::string b) {
+  if (a == b)
+    return false;
+  if (a == "com")
+    return true;
+  if (a == "net")
+    return b != "com";
+  if (a == "org")
+    return b != "com" && b != "net";
+  return false;
+}
+
+// Names of API modules that do not require a permission.
+const char kBrowserActionModuleName[] = "browserAction";
+const char kBrowserActionsModuleName[] = "browserActions";
+const char kDevToolsModuleName[] = "devtools";
+const char kExtensionModuleName[] = "extension";
+const char kI18NModuleName[] = "i18n";
+const char kOmniboxModuleName[] = "omnibox";
+const char kPageActionModuleName[] = "pageAction";
+const char kPageActionsModuleName[] = "pageActions";
+const char kTestModuleName[] = "test";
+const char kTypesModuleName[] = "types";
+
+// Names of modules that can be used without listing it in the permissions
+// section of the manifest.
+const char* kNonPermissionModuleNames[] = {
+  kBrowserActionModuleName,
+  kBrowserActionsModuleName,
+  kDevToolsModuleName,
+  kExtensionModuleName,
+  kI18NModuleName,
+  kOmniboxModuleName,
+  kPageActionModuleName,
+  kPageActionsModuleName,
+  kTestModuleName,
+  kTypesModuleName
+};
+const size_t kNumNonPermissionModuleNames =
+    arraysize(kNonPermissionModuleNames);
+
+// Names of functions (within modules requiring permissions) that can be used
+// without asking for the module permission. In other words, functions you can
+// use with no permissions specified.
+const char* kNonPermissionFunctionNames[] = {
+  "tabs.create",
+  "tabs.onRemoved",
+  "tabs.remove",
+  "tabs.update",
+};
+const size_t kNumNonPermissionFunctionNames =
+    arraysize(kNonPermissionFunctionNames);
+
+const char kOldUnlimitedStoragePermission[] = "unlimited_storage";
+const char kWindowsPermission[] = "windows";
+
+void AddPatternsAndRemovePaths(const URLPatternSet& set, URLPatternSet* out) {
+  CHECK(out);
+  const URLPatternList& patterns = set.patterns();
+  for (size_t i = 0; i < patterns.size(); ++i) {
+    URLPattern p = patterns.at(i);
+    p.SetPath("/*");
+    out->AddPattern(p);
+  }
+}
+
+} // namespace
+
+//
+// PermissionMessage
+//
+
+// static
+ExtensionPermissionMessage ExtensionPermissionMessage::CreateFromHostList(
+    const std::vector<std::string>& hosts) {
+  CHECK(hosts.size() > 0);
+  ID message_id;
+  string16 message;
+  switch (hosts.size()) {
+    case 1:
+      message_id = kHosts1;
+      message = l10n_util::GetStringFUTF16(IDS_EXTENSION_PROMPT_WARNING_1_HOST,
+                                           UTF8ToUTF16(hosts[0]));
+      break;
+    case 2:
+      message_id = kHosts2;
+      message = l10n_util::GetStringFUTF16(IDS_EXTENSION_PROMPT_WARNING_2_HOSTS,
+                                           UTF8ToUTF16(hosts[0]),
+                                           UTF8ToUTF16(hosts[1]));
+      break;
+    case 3:
+      message_id = kHosts3;
+      message = l10n_util::GetStringFUTF16(IDS_EXTENSION_PROMPT_WARNING_3_HOSTS,
+                                           UTF8ToUTF16(hosts[0]),
+                                           UTF8ToUTF16(hosts[1]),
+                                           UTF8ToUTF16(hosts[2]));
+      break;
+    default:
+      message_id = kHosts4OrMore;
+      message = l10n_util::GetStringFUTF16(
+          IDS_EXTENSION_PROMPT_WARNING_4_OR_MORE_HOSTS,
+          UTF8ToUTF16(hosts[0]),
+          UTF8ToUTF16(hosts[1]),
+          base::IntToString16(hosts.size() - 2));
+      break;
+  }
+
+  return ExtensionPermissionMessage(message_id, message);
+}
+
+ExtensionPermissionMessage::ExtensionPermissionMessage(
+    ExtensionPermissionMessage::ID id, const string16& message)
+  : id_(id), message_(message) {
+}
+
+ExtensionPermissionMessage::~ExtensionPermissionMessage() {
+}
+
+//
+// ExtensionPermission
+//
+
+ExtensionPermissionMessage ExtensionAPIPermission::GetMessage() const {
+  return ExtensionPermissionMessage(
+      message_id_, l10n_util::GetStringUTF16(l10n_message_id_));
+}
+
+ExtensionAPIPermission::ExtensionAPIPermission(
+    ID id,
+    const char* name,
+    bool is_hosted_app,
+    bool is_component_only,
+    int l10n_message_id,
+    ExtensionPermissionMessage::ID message_id,
+    bool implies_full_access,
+    bool implies_full_url_access)
+    : id_(id),
+      name_(name),
+      implies_full_access_(implies_full_access),
+      implies_full_url_access_(implies_full_url_access),
+      is_hosted_app_(is_hosted_app),
+      is_component_only_(is_component_only),
+      l10n_message_id_(l10n_message_id),
+      message_id_(message_id) {
+}
+
+ExtensionAPIPermission::~ExtensionAPIPermission() {
+}
+
+//
+// ExtensionPermissionsInfo
+//
+
+// static
+ExtensionPermissionsInfo* ExtensionPermissionsInfo::GetInstance() {
+  return Singleton<ExtensionPermissionsInfo>::get();
+}
+
+ExtensionAPIPermission* ExtensionPermissionsInfo::GetByID(
+    ExtensionAPIPermission::ID id) {
+  IDMap::iterator i = id_map_.find(id);
+  return (i == id_map_.end()) ? NULL : i->second;
+}
+
+ExtensionAPIPermission* ExtensionPermissionsInfo::GetByName(std::string name) {
+  NameMap::iterator i = name_map_.find(name);
+  return (i == name_map_.end()) ? NULL : i->second;
+}
+
+ExtensionAPIPermissionSet ExtensionPermissionsInfo::GetAll() {
+  ExtensionAPIPermissionSet permissions;
+  for (IDMap::const_iterator i = id_map_.begin(); i != id_map_.end(); ++i)
+    permissions.insert(i->second->id());
+  return permissions;
+}
+
+ExtensionAPIPermissionSet ExtensionPermissionsInfo::GetAllByName(
+    const std::set<std::string>& permission_names) {
+  ExtensionAPIPermissionSet permissions;
+  for (std::set<std::string>::const_iterator i = permission_names.begin();
+       i != permission_names.end(); ++i) {
+    ExtensionAPIPermission* permission = GetByName(*i);
+    if (permission)
+      permissions.insert(permission->id());
+  }
+  return permissions;
+}
+
+ExtensionPermissionsInfo::~ExtensionPermissionsInfo() {
+  for (IDMap::iterator i = id_map_.begin(); i != id_map_.end(); ++i)
+    delete i->second;
+}
+
+ExtensionPermissionsInfo::ExtensionPermissionsInfo()
+    : hosted_app_permission_count_(0),
+      permission_count_(0) {
+  // Hosted app permissions
+  RegisterHostedAppPermission(
+      ExtensionAPIPermission::kBackground, "background", 0,
+      ExtensionPermissionMessage::kNone);
+  RegisterHostedAppPermission(
+      ExtensionAPIPermission::kClipboardRead, "clipboardRead",
+      IDS_EXTENSION_PROMPT_WARNING_CLIPBOARD,
+      ExtensionPermissionMessage::kClipboard);
+  RegisterHostedAppPermission(
+      ExtensionAPIPermission::kClipboardWrite, "clipboardWrite",  0,
+      ExtensionPermissionMessage::kNone);
+  RegisterHostedAppPermission(
+      ExtensionAPIPermission::kChromePrivate, "chromePrivate", 0,
+      ExtensionPermissionMessage::kNone);
+  RegisterHostedAppPermission(
+      ExtensionAPIPermission::kExperimental, "experimental", 0,
+      ExtensionPermissionMessage::kNone);
+  RegisterHostedAppPermission(
+      ExtensionAPIPermission::kGeolocation, "geolocation",
+      IDS_EXTENSION_PROMPT_WARNING_GEOLOCATION,
+      ExtensionPermissionMessage::kGeolocation);
+  RegisterHostedAppPermission(
+      ExtensionAPIPermission::kNotification, "notifications", 0,
+      ExtensionPermissionMessage::kNone);
+  RegisterHostedAppPermission(
+      ExtensionAPIPermission::kUnlimitedStorage, "unlimitedStorage", 0,
+      ExtensionPermissionMessage::kNone);
+
+  // Hosted app and private permissions.
+  RegisterPermission(
+      ExtensionAPIPermission::kWebstorePrivate, "webstorePrivate", 0,
+      ExtensionPermissionMessage::kNone,
+      true, true, false, false);
+
+  // Extension permissions.
+  RegisterExtensionPermission(
+      ExtensionAPIPermission::kBookmark, "bookmarks",
+      IDS_EXTENSION_PROMPT_WARNING_BOOKMARKS,
+      ExtensionPermissionMessage::kBookmarks);
+  RegisterExtensionPermission(
+      ExtensionAPIPermission::kContentSettings, "contentSettings", 0,
+      ExtensionPermissionMessage::kNone);
+  RegisterExtensionPermission(
+      ExtensionAPIPermission::kContextMenus, "contextMenus", 0,
+      ExtensionPermissionMessage::kNone);
+  RegisterExtensionPermission(
+      ExtensionAPIPermission::kCookie, "cookies", 0,
+      ExtensionPermissionMessage::kNone);
+  RegisterExtensionPermission(
+      ExtensionAPIPermission::kDebugger, "debugger",
+      IDS_EXTENSION_PROMPT_WARNING_DEBUGGER,
+      ExtensionPermissionMessage::kDebugger);
+  RegisterExtensionPermission(
+      ExtensionAPIPermission::kFileBrowserHandler, "fileBrowserHandler", 0,
+      ExtensionPermissionMessage::kNone);
+  RegisterExtensionPermission(
+      ExtensionAPIPermission::kHistory, "history",
+      IDS_EXTENSION_PROMPT_WARNING_BROWSING_HISTORY,
+      ExtensionPermissionMessage::kBrowsingHistory);
+  RegisterExtensionPermission(
+      ExtensionAPIPermission::kIdle, "idle", 0,
+      ExtensionPermissionMessage::kNone);
+  RegisterExtensionPermission(
+      ExtensionAPIPermission::kManagement, "management",
+      IDS_EXTENSION_PROMPT_WARNING_MANAGEMENT,
+      ExtensionPermissionMessage::kManagement);
+  RegisterExtensionPermission(
+      ExtensionAPIPermission::kTab, "tabs",
+      IDS_EXTENSION_PROMPT_WARNING_TABS,
+      ExtensionPermissionMessage::kTabs);
+  RegisterExtensionPermission(
+      ExtensionAPIPermission::kWebSocketProxyPrivate,
+      "webSocketProxyPrivate", 0,
+      ExtensionPermissionMessage::kNone);
+
+  // Private permissions
+  RegisterPrivatePermission(
+      ExtensionAPIPermission::kChromeosInfoPrivate, "chromeosInfoPrivate");
+  RegisterPrivatePermission(
+      ExtensionAPIPermission::kFileBrowserPrivate, "fileBrowserPrivate");
+  RegisterPrivatePermission(
+      ExtensionAPIPermission::kMediaPlayerPrivate, "mediaPlayerPrivate");
+
+  // Full url access permissions.
+  RegisterPermission(
+      ExtensionAPIPermission::kProxy, "proxy", 0,
+      ExtensionPermissionMessage::kNone, false, false, false, true);
+
+  RegisterPermission(
+      ExtensionAPIPermission::kDevtools, "devtools", 0,
+      ExtensionPermissionMessage::kNone, false, false, false, true);
+
+  RegisterPermission(
+      ExtensionAPIPermission::kPlugin, "plugin",
+      IDS_EXTENSION_PROMPT_WARNING_FULL_ACCESS,
+      ExtensionPermissionMessage::kFullAccess, false, false, true, true);
+
+  RegisterPermission(
+      ExtensionAPIPermission::kDefault, "default", 0,
+      ExtensionPermissionMessage::kNone, false, false, false, false);
+
+  // Register Aliases
+  RegisterAlias("unlimitedStorage", kOldUnlimitedStoragePermission);
+  RegisterAlias("tabs", kWindowsPermission);
+}
+
+void ExtensionPermissionsInfo::RegisterAlias(
+    const char* name, const char* alias) {
+  CHECK(name_map_.find(name) != name_map_.end());
+  CHECK(name_map_.find(alias) == name_map_.end());
+  name_map_[alias] = name_map_[name];
+}
+
+void ExtensionPermissionsInfo::RegisterExtensionPermission(
+    ExtensionAPIPermission::ID id,
+    const char* name,
+    int l10n_message_id,
+    ExtensionPermissionMessage::ID message_id) {
+  RegisterPermission(id, name, l10n_message_id, message_id,
+                     false, false, false, false);
+}
+
+void ExtensionPermissionsInfo::RegisterHostedAppPermission(
+    ExtensionAPIPermission::ID id,
+    const char* name,
+    int l10n_message_id,
+    ExtensionPermissionMessage::ID message_id) {
+  RegisterPermission(id, name, l10n_message_id, message_id,
+                     true, false, false, false);
+}
+
+void ExtensionPermissionsInfo::RegisterPrivatePermission(
+    ExtensionAPIPermission::ID id, const char* name) {
+  RegisterPermission(id, name, 0, ExtensionPermissionMessage::kNone,
+                     false, true, false, false);
+}
+
+void ExtensionPermissionsInfo::RegisterPermission(
+    ExtensionAPIPermission::ID id,
+    const char* name,
+    int l10n_message_id,
+    ExtensionPermissionMessage::ID message_id,
+    bool is_hosted_app,
+    bool is_component_only,
+    bool implies_full_access,
+    bool implies_full_url_access) {
+  CHECK(id_map_.find(id) == id_map_.end());
+  CHECK(name_map_.find(name) == name_map_.end());
+
+  ExtensionAPIPermission* permission =
+      new ExtensionAPIPermission(id,
+                                 name,
+                                 is_hosted_app,
+                                 is_component_only,
+                                 l10n_message_id,
+                                 message_id,
+                                 implies_full_access,
+                                 implies_full_url_access);
+  id_map_[id] = permission;
+  name_map_[name] = permission;
+
+  permission_count_++;
+  if (permission->is_hosted_app())
+    hosted_app_permission_count_++;
+}
+
+//
+// ExtensionPermissionSet
+//
+
+ExtensionPermissionSet::ExtensionPermissionSet() {
+}
+
+ExtensionPermissionSet::ExtensionPermissionSet(
+    const Extension* extension,
+    const ExtensionAPIPermissionSet& apis,
+    const URLPatternSet& explicit_hosts)
+  : apis_(apis) {
+  CHECK(extension);
+  AddPatternsAndRemovePaths(explicit_hosts, &explicit_hosts_);
+  InitImplicitExtensionPermissions(extension);
+  InitEffectiveHosts();
+}
+
+ExtensionPermissionSet::ExtensionPermissionSet(
+    const ExtensionAPIPermissionSet& apis,
+    const URLPatternSet& explicit_hosts,
+    const URLPatternSet& scriptable_hosts)
+  : apis_(apis),
+    scriptable_hosts_(scriptable_hosts) {
+  AddPatternsAndRemovePaths(explicit_hosts, &explicit_hosts_);
+  InitEffectiveHosts();
+}
+
+ExtensionPermissionSet::~ExtensionPermissionSet() {
+}
+
+// static
+ExtensionPermissionSet* ExtensionPermissionSet::CreateUnion(
+    const ExtensionPermissionSet* set1,
+    const ExtensionPermissionSet* set2) {
+  ExtensionPermissionSet empty;
+  const ExtensionPermissionSet* set1_safe = (set1 == NULL) ? &empty : set1;
+  const ExtensionPermissionSet* set2_safe = (set2 == NULL) ? &empty : set2;
+
+  ExtensionAPIPermissionSet apis;
+  std::set_union(set1_safe->apis().begin(), set1_safe->apis().end(),
+                 set2_safe->apis().begin(), set2_safe->apis().end(),
+                 std::insert_iterator<ExtensionAPIPermissionSet>(
+                     apis, apis.begin()));
+
+  URLPatternSet explicit_hosts;
+  URLPatternSet scriptable_hosts;
+  URLPatternSet::CreateUnion(set1_safe->explicit_hosts(),
+                             set2_safe->explicit_hosts(),
+                             &explicit_hosts);
+  URLPatternSet::CreateUnion(set1_safe->scriptable_hosts(),
+                             set2_safe->scriptable_hosts(),
+                             &scriptable_hosts);
+
+  return new ExtensionPermissionSet(apis, explicit_hosts, scriptable_hosts);
+}
+
+std::set<std::string> ExtensionPermissionSet::GetAPIsAsStrings() const {
+  ExtensionPermissionsInfo* info = ExtensionPermissionsInfo::GetInstance();
+  std::set<std::string> apis_str;
+  for (ExtensionAPIPermissionSet::const_iterator i = apis_.begin();
+       i != apis_.end(); ++i) {
+    ExtensionAPIPermission* permission = info->GetByID(*i);
+    if (permission)
+      apis_str.insert(permission->name());
+  }
+  return apis_str;
+}
+
+std::vector<std::string>
+    ExtensionPermissionSet::GetDistinctHostsForDisplay() const {
+  return GetDistinctHosts(effective_hosts_.patterns(), true);
+}
+
+ExtensionPermissionMessages
+    ExtensionPermissionSet::GetPermissionMessages() const {
+  ExtensionPermissionMessages messages;
+
+  if (HasEffectiveFullAccess()) {
+    messages.push_back(ExtensionPermissionMessage(
+        ExtensionPermissionMessage::kFullAccess,
+        l10n_util::GetStringUTF16(IDS_EXTENSION_PROMPT_WARNING_FULL_ACCESS)));
+    return messages;
+  }
+
+  if (HasEffectiveAccessToAllHosts()) {
+    messages.push_back(ExtensionPermissionMessage(
+        ExtensionPermissionMessage::kHostsAll,
+        l10n_util::GetStringUTF16(IDS_EXTENSION_PROMPT_WARNING_ALL_HOSTS)));
+  } else {
+    std::vector<std::string> hosts = GetDistinctHostsForDisplay();
+    if (!hosts.empty())
+      messages.push_back(ExtensionPermissionMessage::CreateFromHostList(hosts));
+  }
+
+  std::set<ExtensionPermissionMessage> simple_msgs =
+      GetSimplePermissionMessages();
+  messages.insert(messages.end(), simple_msgs.begin(), simple_msgs.end());
+
+  return messages;
+}
+
+std::vector<string16> ExtensionPermissionSet::GetWarningMessages() const {
+  std::vector<string16> messages;
+  ExtensionPermissionMessages permissions = GetPermissionMessages();
+  for (ExtensionPermissionMessages::const_iterator i = permissions.begin();
+       i != permissions.end(); ++i)
+    messages.push_back(i->message());
+  return messages;
+}
+
+bool ExtensionPermissionSet::IsEmpty() const {
+  // Not default if any host permissions are present.
+  if (!(explicit_hosts().is_empty() && scriptable_hosts().is_empty()))
+    return false;
+
+  // Or if it has no api permissions.
+  return apis().empty();
+}
+
+bool ExtensionPermissionSet::HasAPIPermission(
+    ExtensionAPIPermission::ID permission) const {
+  return apis().find(permission) != apis().end();
+}
+
+bool ExtensionPermissionSet::HasAccessToFunction(
+    const std::string& function_name) const {
+  // TODO(jstritar): Embed this information in each permission and add a method
+  // like GrantsAccess(function_name) to ExtensionAPIPermission. A "default"
+  // permission can then handle the modules and functions that everyone can
+  // access.
+  std::string permission_name = function_name;
+
+  for (size_t i = 0; i < kNumNonPermissionFunctionNames; ++i) {
+    if (permission_name == kNonPermissionFunctionNames[i])
+      return true;
+  }
+
+  // See if this is a function or event name first and strip out the package.
+  // Functions will be of the form package.function
+  // Events will be of the form package/id or package.optional.stuff
+  size_t separator = function_name.find_first_of("./");
+  if (separator != std::string::npos)
+    permission_name = function_name.substr(0, separator);
+
+  ExtensionAPIPermission* permission =
+      ExtensionPermissionsInfo::GetInstance()->GetByName(permission_name);
+  if (permission && apis_.count(permission->id()))
+    return true;
+
+  for (size_t i = 0; i < kNumNonPermissionModuleNames; ++i) {
+    if (permission_name == kNonPermissionModuleNames[i]) {
+      return true;
+    }
+  }
+
+  return false;
+}
+
+bool ExtensionPermissionSet::HasExplicitAccessToOrigin(
+    const GURL& origin) const {
+  return explicit_hosts().MatchesURL(origin);
+}
+
+bool ExtensionPermissionSet::HasScriptableAccessToURL(
+    const GURL& origin) const {
+  // We only need to check our host list to verify access. The host list should
+  // already reflect any special rules (such as chrome://favicon, component
+  // all hosts access, etc.).
+  return scriptable_hosts().MatchesURL(origin);
+}
+
+bool ExtensionPermissionSet::HasEffectiveAccessToAllHosts() const {
+  // There are two ways this set can have effective access to all hosts:
+  //  1) it has an <all_urls> URL pattern.
+  //  2) it has a named permission with implied full URL access.
+  const URLPatternList patterns = effective_hosts().patterns();
+  for (URLPatternList::const_iterator host = patterns.begin();
+       host != patterns.end(); ++host) {
+    if (host->match_all_urls() ||
+        (host->match_subdomains() && host->host().empty()))
+      return true;
+  }
+
+  ExtensionPermissionsInfo* info = ExtensionPermissionsInfo::GetInstance();
+  for (ExtensionAPIPermissionSet::const_iterator i = apis().begin();
+       i != apis().end(); ++i) {
+    ExtensionAPIPermission* permission = info->GetByID(*i);
+    if (permission->implies_full_url_access())
+      return true;
+  }
+  return false;
+}
+
+bool ExtensionPermissionSet::HasEffectiveAccessToURL(
+    const GURL& url) const {
+  return effective_hosts().MatchesURL(url);
+}
+
+bool ExtensionPermissionSet::HasEffectiveFullAccess() const {
+  ExtensionPermissionsInfo* info = ExtensionPermissionsInfo::GetInstance();
+  for (ExtensionAPIPermissionSet::const_iterator i = apis().begin();
+       i != apis().end(); ++i) {
+    ExtensionAPIPermission* permission = info->GetByID(*i);
+    if (permission->implies_full_access())
+      return true;
+  }
+  return false;
+}
+
+bool ExtensionPermissionSet::HasPrivatePermissions() const {
+  ExtensionPermissionsInfo* info = ExtensionPermissionsInfo::GetInstance();
+  for (ExtensionAPIPermissionSet::const_iterator i = apis_.begin();
+       i != apis_.end(); ++i) {
+    ExtensionAPIPermission* permission = info->GetByID(*i);
+    if (permission && permission->is_component_only())
+      return true;
+  }
+  return false;
+}
+
+bool ExtensionPermissionSet::HasLessPrivilegesThan(
+    const ExtensionPermissionSet* permissions) const {
+  // Things can't get worse than native code access.
+  if (HasEffectiveFullAccess())
+    return false;
+
+  // Otherwise, it's a privilege increase if the new one has full access.
+  if (permissions->HasEffectiveFullAccess())
+    return true;
+
+  if (HasLessHostPrivilegesThan(permissions))
+    return true;
+
+  if (HasLessAPIPrivilegesThan(permissions))
+    return true;
+
+  return false;
+}
+
+// static
+std::vector<std::string> ExtensionPermissionSet::GetDistinctHosts(
+    const URLPatternList& host_patterns, bool include_rcd) {
+  // Use a vector to preserve order (also faster than a map on small sets).
+  // Each item is a host split into two parts: host without RCDs and
+  // current best RCD.
+  typedef std::vector<std::pair<std::string, std::string> > HostVector;
+  HostVector hosts_best_rcd;
+  for (size_t i = 0; i < host_patterns.size(); ++i) {
+    std::string host = host_patterns[i].host();
+
+    // Add the subdomain wildcard back to the host, if necessary.
+    if (host_patterns[i].match_subdomains())
+      host = "*." + host;
+
+    // If the host has an RCD, split it off so we can detect duplicates.
+    std::string rcd;
+    size_t reg_len = net::RegistryControlledDomainService::GetRegistryLength(
+        host, false);
+    if (reg_len && reg_len != std::string::npos) {
+      if (include_rcd)  // else leave rcd empty
+        rcd = host.substr(host.size() - reg_len);
+      host = host.substr(0, host.size() - reg_len);
+    }
+
+    // Check if we've already seen this host.
+    HostVector::iterator it = hosts_best_rcd.begin();
+    for (; it != hosts_best_rcd.end(); ++it) {
+      if (it->first == host)
+        break;
+    }
+    // If this host was found, replace the RCD if this one is better.
+    if (it != hosts_best_rcd.end()) {
+      if (include_rcd && RcdBetterThan(rcd, it->second))
+        it->second = rcd;
+    } else {  // Previously unseen host, append it.
+      hosts_best_rcd.push_back(std::make_pair(host, rcd));
+    }
+  }
+
+  // Build up the final vector by concatenating hosts and RCDs.
+  std::vector<std::string> distinct_hosts;
+  for (HostVector::iterator it = hosts_best_rcd.begin();
+       it != hosts_best_rcd.end(); ++it)
+    distinct_hosts.push_back(it->first + it->second);
+  return distinct_hosts;
+}
+
+void ExtensionPermissionSet::InitEffectiveHosts() {
+  effective_hosts_.ClearPatterns();
+
+  if (HasEffectiveAccessToAllHosts()) {
+    URLPattern all_urls(URLPattern::SCHEME_ALL);
+    all_urls.set_match_all_urls(true);
+    effective_hosts_.AddPattern(all_urls);
+    return;
+  }
+
+  URLPatternSet::CreateUnion(
+      explicit_hosts(), scriptable_hosts(), &effective_hosts_);
+}
+
+void ExtensionPermissionSet::InitImplicitExtensionPermissions(
+    const Extension* extension) {
+  // Add the implied permissions.
+  if (!extension->plugins().empty())
+    apis_.insert(ExtensionAPIPermission::kPlugin);
+
+  if (!extension->devtools_url().is_empty())
+    apis_.insert(ExtensionAPIPermission::kDevtools);
+
+  // Add the scriptable hosts.
+  for (UserScriptList::const_iterator content_script =
+           extension->content_scripts().begin();
+       content_script != extension->content_scripts().end(); ++content_script) {
+    URLPatternList::const_iterator pattern =
+        content_script->url_patterns().begin();
+    for (; pattern != content_script->url_patterns().end(); ++pattern)
+      scriptable_hosts_.AddPattern(*pattern);
+  }
+}
+
+std::set<ExtensionPermissionMessage>
+    ExtensionPermissionSet::GetSimplePermissionMessages() const {
+  std::set<ExtensionPermissionMessage> messages;
+  ExtensionPermissionsInfo* info = ExtensionPermissionsInfo::GetInstance();
+  for (ExtensionAPIPermissionSet::const_iterator i = apis_.begin();
+       i != apis_.end(); ++i) {
+    DCHECK_GT(ExtensionPermissionMessage::kNone,
+              ExtensionPermissionMessage::kUnknown);
+    ExtensionAPIPermission* perm = info->GetByID(*i);
+    if (perm && perm->message_id() > ExtensionPermissionMessage::kNone)
+      messages.insert(perm->GetMessage());
+  }
+  return messages;
+}
+
+bool ExtensionPermissionSet::HasLessAPIPrivilegesThan(
+    const ExtensionPermissionSet* permissions) const {
+  if (permissions == NULL)
+    return false;
+
+  ExtensionAPIPermissionSet new_apis = permissions->apis_;
+  ExtensionAPIPermissionSet new_apis_only;
+  std::set_difference(new_apis.begin(), new_apis.end(),
+                      apis_.begin(), apis_.end(),
+                      std::inserter(new_apis_only, new_apis_only.begin()));
+
+  ExtensionPermissionsInfo* info = ExtensionPermissionsInfo::GetInstance();
+
+  // Ignore API permissions that don't require user approval when deciding if
+  // an extension has increased its privileges.
+  for (ExtensionAPIPermissionSet::iterator i = new_apis_only.begin();
+       i != new_apis_only.end(); ++i) {
+    ExtensionAPIPermission* perm = info->GetByID(*i);
+    if (perm && perm->message_id() > ExtensionPermissionMessage::kNone)
+      return true;
+  }
+  return false;
+}
+
+bool ExtensionPermissionSet::HasLessHostPrivilegesThan(
+    const ExtensionPermissionSet* permissions) const {
+  // If this permission set can access any host, then it can't be elevated.
+  if (HasEffectiveAccessToAllHosts())
+    return false;
+
+  // Likewise, if the other permission set has full host access, then it must be
+  // a privilege increase.
+  if (permissions->HasEffectiveAccessToAllHosts())
+    return true;
+
+  const URLPatternList old_list = effective_hosts().patterns();
+  const URLPatternList new_list = permissions->effective_hosts().patterns();
+
+  // TODO(jstritar): This is overly conservative with respect to subdomains.
+  // For example, going from *.google.com to www.google.com will be
+  // considered an elevation, even though it is not (http://crbug.com/65337).
+  std::vector<std::string> new_hosts = GetDistinctHosts(new_list, false);
+  std::vector<std::string> old_hosts = GetDistinctHosts(old_list, false);
+
+  std::set<std::string> old_hosts_set(old_hosts.begin(), old_hosts.end());
+  std::set<std::string> new_hosts_set(new_hosts.begin(), new_hosts.end());
+  std::set<std::string> new_hosts_only;
+
+  std::set_difference(new_hosts_set.begin(), new_hosts_set.end(),
+                      old_hosts_set.begin(), old_hosts_set.end(),
+                      std::inserter(new_hosts_only, new_hosts_only.begin()));
+
+  return !new_hosts_only.empty();
+}