[extensions] Stop parsing webstore urls so much

chrome/common/extensions/chrome_extensions_client.cc

Index: chrome/common/extensions/chrome_extensions_client.cc
diff --git a/chrome/common/extensions/chrome_extensions_client.cc b/chrome/common/extensions/chrome_extensions_client.cc
index 2fe9459e2de6cd408837a4d51029828be1a3fff7..9a4a929ae7b1dddc2643342e158c230cbd045d26 100644
--- a/chrome/common/extensions/chrome_extensions_client.cc
+++ b/chrome/common/extensions/chrome_extensions_client.cc
@@ -281,12 +281,20 @@ std::string ChromeExtensionsClient::GetWebstoreBaseURL() const {
   return gallery_prefix;
 }
 
-std::string ChromeExtensionsClient::GetWebstoreUpdateURL() const {
+const GURL& ChromeExtensionsClient::GetWebstoreUpdateURL() const {
+  // Browser tests like to alter the command line at runtime with new update
+  // URLs. Just update the cached value of the update url (to avoid reparsing
+  // it) if the value has changed.
   base::CommandLine* cmdline = base::CommandLine::ForCurrentProcess();
-  if (cmdline->HasSwitch(switches::kAppsGalleryUpdateURL))
-    return cmdline->GetSwitchValueASCII(switches::kAppsGalleryUpdateURL);
-  else
-    return extension_urls::GetDefaultWebstoreUpdateUrl().spec();
+  if (cmdline->HasSwitch(switches::kAppsGalleryUpdateURL)) {
+    std::string url =
+        cmdline->GetSwitchValueASCII(switches::kAppsGalleryUpdateURL);
+    if (webstore_update_url_ != url)
+      webstore_update_url_ = GURL(url);
+  } else if (webstore_update_url_.is_empty()) {
+    webstore_update_url_ = GURL(extension_urls::GetDefaultWebstoreUpdateUrl());
+  }
+  return webstore_update_url_;
 }
 
 bool ChromeExtensionsClient::IsBlacklistUpdateURL(const GURL& url) const {