Identity extension API impl: Split constants into their own file

chrome/browser/extensions/api/identity/identity_constants.h

Index: chrome/browser/extensions/api/identity/identity_constants.h
diff --git a/chrome/browser/extensions/api/identity/identity_constants.h b/chrome/browser/extensions/api/identity/identity_constants.h
new file mode 100644
index 0000000000000000000000000000000000000000..8fc01ff187d864a2ee849ba083f69de533dd54b3
--- /dev/null
+++ b/chrome/browser/extensions/api/identity/identity_constants.h
@@ -0,0 +1,28 @@
+// Copyright 2017 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#ifndef CHROME_BROWSER_EXTENSIONS_API_IDENTITY_IDENTITY_CONSTANTS_H_
+#define CHROME_BROWSER_EXTENSIONS_API_IDENTITY_IDENTITY_CONSTANTS_H_
+
+namespace extensions {
+
+namespace identity_constants {
+extern const char kInvalidClientId[];
+extern const char kInvalidScopes[];
+extern const char kAuthFailure[];
+extern const char kNoGrant[];
+extern const char kUserRejected[];
+extern const char kUserNotSignedIn[];
+extern const char kInteractionRequired[];
+extern const char kInvalidRedirect[];
+extern const char kOffTheRecord[];
+extern const char kPageLoadFailure[];
+extern const char kCanceled[];
+
+extern const int kCachedIssueAdviceTTLSeconds;
+}  // namespace identity_constants
+
+}  // namespace extensions
+
+#endif  // CHROME_BROWSER_EXTENSIONS_API_IDENTITY_IDENTITY_CONSTANTS_H_