Move impl of identity.LaunchWebAuthFlow() extension API to its own file

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

Index: chrome/browser/extensions/api/identity/identity_launch_web_auth_flow_function.h
diff --git a/chrome/browser/extensions/api/identity/identity_launch_web_auth_flow_function.h b/chrome/browser/extensions/api/identity/identity_launch_web_auth_flow_function.h
new file mode 100644
index 0000000000000000000000000000000000000000..a975f2eb10b6186e88413efafb69b371f75ad049
--- /dev/null
+++ b/chrome/browser/extensions/api/identity/identity_launch_web_auth_flow_function.h
@@ -0,0 +1,45 @@
+// 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_LAUNCH_WEB_AUTH_FLOW_FUNCTION_H_
+#define CHROME_BROWSER_EXTENSIONS_API_IDENTITY_IDENTITY_LAUNCH_WEB_AUTH_FLOW_FUNCTION_H_
+
+#include <string>
+
+#include "chrome/browser/extensions/api/identity/web_auth_flow.h"
+#include "chrome/browser/extensions/chrome_extension_function.h"
+#include "extensions/browser/extension_function_histogram_value.h"
+
+namespace extensions {
+
+class IdentityLaunchWebAuthFlowFunction : public ChromeAsyncExtensionFunction,
+                                          public WebAuthFlow::Delegate {
+ public:
+  DECLARE_EXTENSION_FUNCTION("identity.launchWebAuthFlow",
+                             EXPERIMENTAL_IDENTITY_LAUNCHWEBAUTHFLOW);
+
+  IdentityLaunchWebAuthFlowFunction();
+
+  // Tests may override extension_id.
+  void InitFinalRedirectURLPrefixForTest(const std::string& extension_id);
+
+ private:
+  ~IdentityLaunchWebAuthFlowFunction() override;
+  bool RunAsync() override;
+
+  // WebAuthFlow::Delegate implementation.
+  void OnAuthFlowFailure(WebAuthFlow::Failure failure) override;
+  void OnAuthFlowURLChange(const GURL& redirect_url) override;
+  void OnAuthFlowTitleChange(const std::string& title) override {}
+
+  // Helper to initialize final URL prefix.
+  void InitFinalRedirectURLPrefix(const std::string& extension_id);
+
+  std::unique_ptr<WebAuthFlow> auth_flow_;
+  GURL final_url_prefix_;
+};
+
+}  // namespace extensions
+
+#endif  // CHROME_BROWSER_EXTENSIONS_API_IDENTITY_IDENTITY_LAUNCH_WEB_AUTH_FLOW_FUNCTION_H_