Disconnect one click sign in code. The code itself will be removed in followup

chrome/browser/chrome_content_browser_client.cc

Index: chrome/browser/chrome_content_browser_client.cc
diff --git a/chrome/browser/chrome_content_browser_client.cc b/chrome/browser/chrome_content_browser_client.cc
index dc10e10aa2c47238560178fd38d14a65356a3f47..3ee8858843e64abb67192feb6366b83f5d5f6bb1 100644
--- a/chrome/browser/chrome_content_browser_client.cc
+++ b/chrome/browser/chrome_content_browser_client.cc
@@ -802,8 +802,7 @@ std::string ChromeContentBrowserClient::GetStoragePartitionIdForSite(
   // SiteInstance URL - "chrome-guest://app_id/persist?partition".
   if (site.SchemeIs(content::kGuestScheme)) {
     partition_id = site.spec();
-  } else if (site.GetOrigin().spec() == kChromeUIChromeSigninURL &&
-            !switches::IsEnableWebviewBasedSignin()) {
+  } else if (site.GetOrigin().spec() == kChromeUIChromeSigninURL) {
     // Chrome signin page has an embedded iframe of extension and web content,
     // thus it must be isolated from other webUI pages.
     partition_id = site.GetOrigin().spec();
@@ -867,8 +866,7 @@ void ChromeContentBrowserClient::GetStoragePartitionConfigForSite(
   }
 #endif
 
-  if (!success && (site.GetOrigin().spec() == kChromeUIChromeSigninURL) &&
-      !switches::IsEnableWebviewBasedSignin()) {
+  if (!success && (site.GetOrigin().spec() == kChromeUIChromeSigninURL)) {
     // Chrome signin page has an embedded iframe of extension and web content,
     // thus it must be isolated from other webUI pages.
     *partition_domain = chrome::kChromeUIChromeSigninHost;
@@ -1466,7 +1464,6 @@ void ChromeContentBrowserClient::AppendExtraCommandLineSwitches(
       switches::kEnableOutOfProcessPdf,
       switches::kEnablePluginPlaceholderShadowDom,
       switches::kEnableShowModalDialog,
-      switches::kEnableWebBasedSignin,
       switches::kJavaScriptHarmony,
       switches::kMessageLoopHistogrammer,
       switches::kPlaybackMode,