Avoid parsing the webstore base url so much.

extensions/shell/common/shell_extensions_client.cc

Index: extensions/shell/common/shell_extensions_client.cc
diff --git a/extensions/shell/common/shell_extensions_client.cc b/extensions/shell/common/shell_extensions_client.cc
index 0d2557a75ad8e28f050c6c66f863fd605f6b10dd..ff290854cc048b5b9b8a143c965f8039e96737b9 100644
--- a/extensions/shell/common/shell_extensions_client.cc
+++ b/extensions/shell/common/shell_extensions_client.cc
@@ -77,6 +77,7 @@ base::LazyInstance<ShellPermissionMessageProvider>
 
 ShellExtensionsClient::ShellExtensionsClient()
     : extensions_api_permissions_(ExtensionsAPIPermissions()),
+      webstore_base_url_(extension_urls::kChromeWebstoreBaseURL),
       webstore_update_url_(extension_urls::kChromeWebstoreUpdateURL) {}
 
 ShellExtensionsClient::~ShellExtensionsClient() {
@@ -181,8 +182,8 @@ bool ShellExtensionsClient::ShouldSuppressFatalErrors() const {
 void ShellExtensionsClient::RecordDidSuppressFatalError() {
 }
 
-std::string ShellExtensionsClient::GetWebstoreBaseURL() const {
-  return extension_urls::kChromeWebstoreBaseURL;
+const GURL& ShellExtensionsClient::GetWebstoreBaseURL() const {
+  return webstore_base_url_;
 }
 
 const GURL& ShellExtensionsClient::GetWebstoreUpdateURL() const {