Extensions: Only create Web request rules registry if Declarative Web Request is enabled.

extensions/browser/api/declarative/rules_registry_service.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 "extensions/browser/api/declarative/rules_registry_service.h"
 
 #include <memory>
 
 #include "base/bind.h"
 #include "base/lazy_instance.h"
 #include "base/logging.h"
 #include "base/memory/ptr_util.h"
 #include "content/public/browser/browser_thread.h"
 #include "content/public/browser/render_process_host.h"
 #include "extensions/browser/api/declarative/rules_cache_delegate.h"
 #include "extensions/browser/api/declarative_content/content_rules_registry.h"
 #include "extensions/browser/api/declarative_webrequest/webrequest_constants.h"
 #include "extensions/browser/api/declarative_webrequest/webrequest_rules_registry.h"
 #include "extensions/browser/api/extensions_api_client.h"
 #include "extensions/browser/api/web_request/web_request_api.h"
 #include "extensions/browser/extension_registry.h"
 #include "extensions/common/extension.h"
+#include "extensions/common/features/feature_channel.h"
+#include "extensions/common/features/feature_provider.h"
 
 namespace extensions {
 
 namespace {
 
 // Registers |web_request_rules_registry| on the IO thread.
 void RegisterToExtensionWebRequestEventRouterOnIO(
     content::BrowserContext* browser_context,
     int rules_registry_id,
     scoped_refptr<WebRequestRulesRegistry> web_request_rules_registry) {
@@ skipping 34 matching lines @@
     int rules_registry_id) {
   if (!browser_context_)
     return;
   RulesRegistryKey key(declarative_webrequest_constants::kOnRequest,
                        rules_registry_id);
   // If we can find the key in the |rule_registries_| then we have already
   // installed the default registries.
   if (ContainsKey(rule_registries_, key))
     return;
 
-  // Only cache rules for regular pages.
-  RulesCacheDelegate* web_request_cache_delegate = NULL;

[karandeepb, 2017/02/17 02:07:57]

Wasn't able to find code which relied on the existence of a web request rules
registry.

-  if (rules_registry_id == kDefaultRulesRegistryID) {
-    // Create a RulesCacheDelegate.
-    web_request_cache_delegate =
-        new RulesCacheDelegate(true /*log_storage_init_delay*/);
-    cache_delegates_.push_back(base::WrapUnique(web_request_cache_delegate));
+  // Create a web request rules registry if declarative web request is enabled
+  // on the current channel.
+  const Feature* declarative_web_request =
+      FeatureProvider::GetAPIFeature("declarativeWebRequest");
+  if (declarative_web_request->IsAvailableToChannel(GetCurrentChannel())
+          .is_available()) {
+    // Only cache rules for regular pages.
+    RulesCacheDelegate* web_request_cache_delegate = NULL;

[Devlin, 2017/02/17 19:58:28]

nit: since we're touching this code, update to nullptr

[karandeepb, 2017/02/18 02:00:29]

Done.

+    if (rules_registry_id == kDefaultRulesRegistryID) {
+      // Create a RulesCacheDelegate.
+      web_request_cache_delegate =
+          new RulesCacheDelegate(true /*log_storage_init_delay*/);
+      cache_delegates_.push_back(base::WrapUnique(web_request_cache_delegate));
+    }
+    scoped_refptr<WebRequestRulesRegistry> web_request_rules_registry(
+        new WebRequestRulesRegistry(
+            browser_context_, web_request_cache_delegate, rules_registry_id));
+
+    RegisterRulesRegistry(web_request_rules_registry);
+    content::BrowserThread::PostTask(
+        content::BrowserThread::IO, FROM_HERE,
+        base::Bind(&RegisterToExtensionWebRequestEventRouterOnIO,
+                   browser_context_, rules_registry_id,
+                   web_request_rules_registry));
   }
-  scoped_refptr<WebRequestRulesRegistry> web_request_rules_registry(
-      new WebRequestRulesRegistry(browser_context_, web_request_cache_delegate,
-                                  rules_registry_id));
-
-  RegisterRulesRegistry(web_request_rules_registry);
-  content::BrowserThread::PostTask(
-      content::BrowserThread::IO, FROM_HERE,
-      base::Bind(&RegisterToExtensionWebRequestEventRouterOnIO,
-                 browser_context_, rules_registry_id,
-                 web_request_rules_registry));
 
   // Only create a ContentRulesRegistry for regular pages.
   if (rules_registry_id == kDefaultRulesRegistryID) {
     RulesCacheDelegate* content_rules_cache_delegate =
         new RulesCacheDelegate(false /*log_storage_init_delay*/);
     cache_delegates_.push_back(base::WrapUnique(content_rules_cache_delegate));
     scoped_refptr<ContentRulesRegistry> content_rules_registry =
         ExtensionsAPIClient::Get()->CreateContentRulesRegistry(
             browser_context_, content_rules_cache_delegate);
     if (content_rules_registry.get() != nullptr) {
@@ skipping 115 matching lines @@
 }
 
 void RulesRegistryService::OnExtensionUninstalled(
     content::BrowserContext* browser_context,
     const Extension* extension,
     extensions::UninstallReason reason) {
   NotifyRegistriesHelper(&RulesRegistry::OnExtensionUninstalled, extension);
 }
 
 }  // namespace extensions