Avoid parsing the webstore base url so much.

extensions/test/test_extensions_client.cc

Index: extensions/test/test_extensions_client.cc
diff --git a/extensions/test/test_extensions_client.cc b/extensions/test/test_extensions_client.cc
index 6f223feaa9f512aa4ed4b0c07a43e702143f5802..68233ccd252c6d293ed90f5cab2f60fd8b1c21f2 100644
--- a/extensions/test/test_extensions_client.cc
+++ b/extensions/test/test_extensions_client.cc
@@ -38,7 +38,8 @@ SimpleFeature* CreateFeature() {
 }  // namespace
 
 TestExtensionsClient::TestExtensionsClient()
-    : webstore_update_url_(extension_urls::kChromeWebstoreUpdateURL) {}
+    : webstore_base_url_(extension_urls::kChromeWebstoreBaseURL),
+      webstore_update_url_(extension_urls::kChromeWebstoreUpdateURL) {}
 
 TestExtensionsClient::~TestExtensionsClient() {
 }
@@ -147,8 +148,8 @@ bool TestExtensionsClient::ShouldSuppressFatalErrors() const {
 void TestExtensionsClient::RecordDidSuppressFatalError() {
 }
 
-std::string TestExtensionsClient::GetWebstoreBaseURL() const {
-  return extension_urls::kChromeWebstoreBaseURL;
+const GURL& TestExtensionsClient::GetWebstoreBaseURL() const {
+  return webstore_base_url_;
 }
 
 const GURL& TestExtensionsClient::GetWebstoreUpdateURL() const {