Avoid parsing the webstore base url so much.

chrome/common/extensions/chrome_extensions_client.h

 // Copyright 2013 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_COMMON_EXTENSIONS_CHROME_EXTENSIONS_CLIENT_H_
 #define CHROME_COMMON_EXTENSIONS_CHROME_EXTENSIONS_CLIENT_H_
 
 #include <memory>
 
 #include "base/compiler_specific.h"
@@ skipping 29 matching lines @@
   void SetScriptingWhitelist(const ScriptingWhitelist& whitelist) override;
   const ScriptingWhitelist& GetScriptingWhitelist() const override;
   URLPatternSet GetPermittedChromeSchemeHosts(
       const Extension* extension,
       const APIPermissionSet& api_permissions) const override;
   bool IsScriptableURL(const GURL& url, std::string* error) const override;
   bool IsAPISchemaGenerated(const std::string& name) const override;
   base::StringPiece GetAPISchema(const std::string& name) const override;
   bool ShouldSuppressFatalErrors() const override;
   void RecordDidSuppressFatalError() override;
-  std::string GetWebstoreBaseURL() const override;
+  const GURL& GetWebstoreBaseURL() const override;
   const GURL& GetWebstoreUpdateURL() const override;
   bool IsBlacklistUpdateURL(const GURL& url) const override;
   std::set<base::FilePath> GetBrowserImagePaths(
       const Extension* extension) override;
   bool ExtensionAPIEnabledInExtensionServiceWorkers() const override;
 
   // Get the LazyInstance for ChromeExtensionsClient.
   static ChromeExtensionsClient* GetInstance();
 
  private:
   const ChromeAPIPermissions chrome_api_permissions_;
   const ExtensionsAPIPermissions extensions_api_permissions_;
   const ChromePermissionMessageProvider permission_message_provider_;
 
   // A whitelist of extensions that can script anywhere. Do not add to this
   // list (except in tests) without consulting the Extensions team first.
   // Note: Component extensions have this right implicitly and do not need to be
   // added to this list.
   ScriptingWhitelist scripting_whitelist_;
 
   // Mutable to allow caching in a const method.
+  mutable GURL webstore_base_url_;
   mutable GURL webstore_update_url_;
 
   friend struct base::DefaultLazyInstanceTraits<ChromeExtensionsClient>;
 
   DISALLOW_COPY_AND_ASSIGN(ChromeExtensionsClient);
 };
 
 }  // namespace extensions
 
 #endif  // CHROME_COMMON_EXTENSIONS_CHROME_EXTENSIONS_CLIENT_H_