Export a private webstore API to call into the new inline sign-in flow.

chrome/browser/signin/signin_promo.cc

Index: chrome/browser/signin/signin_promo.cc
diff --git a/chrome/browser/signin/signin_promo.cc b/chrome/browser/signin/signin_promo.cc
index be633aca22a9e59eab23075232c91d18422a8444..82faab613b838696b149ff1ed377b0b4a0cd4851 100644
--- a/chrome/browser/signin/signin_promo.cc
+++ b/chrome/browser/signin/signin_promo.cc
@@ -45,6 +45,7 @@ namespace {
 
 const char kSignInPromoQueryKeyAutoClose[] = "auto_close";
 const char kSignInPromoQueryKeyContinue[] = "continue";
+const char kSignInPromoQueryKeyContinueUrl[] = "continueUrl";
 const char kSignInPromoQueryKeySource[] = "source";
 const char kSignInPromoQueryKeyConstrained[] = "constrained";
 
@@ -178,6 +179,13 @@ GURL GetPromoURL(Source source, bool auto_close) {
 }
 
 GURL GetPromoURL(Source source, bool auto_close, bool is_constrained) {
+  return GetPromoURLWithContinueURL(source, auto_close, is_constrained, GURL());
+}
+
+GURL GetPromoURLWithContinueURL(Source source,
+                                bool auto_close,
+                                bool is_constrained,
+                                GURL continue_url) {
   DCHECK_NE(SOURCE_UNKNOWN, source);
 
   if (!switches::IsEnableWebBasedSignin()) {
@@ -187,6 +195,15 @@ GURL GetPromoURL(Source source, bool auto_close, bool is_constrained) {
       base::StringAppendF(&url, "&%s=1", kSignInPromoQueryKeyAutoClose);
     if (is_constrained)
       base::StringAppendF(&url, "&%s=1", kSignInPromoQueryKeyConstrained);
+    if (!continue_url.is_empty()) {
+      DCHECK(continue_url.is_valid());
+      std::string escaped_continue_url =
+          net::EscapeQueryParamValue(continue_url.spec(), false);
+      base::StringAppendF(&url,
+                          "&%s=%s",
+                          kSignInPromoQueryKeyContinueUrl,
+                          escaped_continue_url.c_str());
+    }
     return GURL(url);
   }
 
@@ -206,14 +223,19 @@ GURL GetPromoURL(Source source, bool auto_close, bool is_constrained) {
   // See OneClickSigninHelper for details.
   std::string query_string = "?service=chromiumsync&sarp=1";
 
-  std::string continue_url = GetLandingURL(kSignInPromoQueryKeySource,
-                                           static_cast<int>(source)).spec();
-  if (auto_close)
-    base::StringAppendF(&continue_url, "&%s=1", kSignInPromoQueryKeyAutoClose);
+  DCHECK(continue_url.is_empty());
+  std::string continue_url_str = GetLandingURL(kSignInPromoQueryKeySource,
+                                               static_cast<int>(source)).spec();
+  if (auto_close) {
+    base::StringAppendF(
+        &continue_url_str, "&%s=1", kSignInPromoQueryKeyAutoClose);
+  }
 
-  base::StringAppendF(&query_string, "&%s=%s", kSignInPromoQueryKeyContinue,
-                      net::EscapeQueryParamValue(
-                          continue_url, false).c_str());
+  base::StringAppendF(
+      &query_string,
+      "&%s=%s",
+      kSignInPromoQueryKeyContinue,
+      net::EscapeQueryParamValue(continue_url_str, false).c_str());
 
   return GaiaUrls::GetInstance()->service_login_url().Resolve(query_string);
 }