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

chrome/browser/extensions/api/webstore_private/webstore_private_api.h

Index: chrome/browser/extensions/api/webstore_private/webstore_private_api.h
diff --git a/chrome/browser/extensions/api/webstore_private/webstore_private_api.h b/chrome/browser/extensions/api/webstore_private/webstore_private_api.h
index 57f2b7a0dbb6d2848d053d22a2a8cd2bb4bc01b9..eb38ccc52c2f6e73612d8b01cf0b4f923770250b 100644
--- a/chrome/browser/extensions/api/webstore_private/webstore_private_api.h
+++ b/chrome/browser/extensions/api/webstore_private/webstore_private_api.h
@@ -304,6 +304,20 @@ class WebstorePrivateIsInIncognitoModeFunction
   virtual bool RunImpl() OVERRIDE;
 };
 
+class WebstorePrivateSignInFunction : public ChromeAsyncExtensionFunction {
+ public:
+  DECLARE_EXTENSION_FUNCTION("webstorePrivate.signIn",
+                             WEBSTOREPRIVATE_SIGNINFUNCTION)
+
+  WebstorePrivateSignInFunction() {}
+
+ protected:
+  virtual ~WebstorePrivateSignInFunction() {}
+
+  // ExtensionFunction:
+  virtual bool RunImpl() OVERRIDE;
+};
+
 }  // namespace extensions
 
 #endif  // CHROME_BROWSER_EXTENSIONS_API_WEBSTORE_PRIVATE_WEBSTORE_PRIVATE_API_H_