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

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

Index: chrome/browser/extensions/api/identity/identity_api.h
diff --git a/chrome/browser/extensions/api/identity/identity_api.h b/chrome/browser/extensions/api/identity/identity_api.h
index 6ee7f6117c82617e5097c5ab27085c8fa36ab802..836da938499a99ba29b070fa5114bb9a92c49692 100644
--- a/chrome/browser/extensions/api/identity/identity_api.h
+++ b/chrome/browser/extensions/api/identity/identity_api.h
@@ -20,6 +20,7 @@
 #include "chrome/browser/extensions/api/identity/gaia_web_auth_flow.h"
 #include "chrome/browser/extensions/api/identity/identity_launch_web_auth_flow_function.h"
 #include "chrome/browser/extensions/api/identity/identity_mint_queue.h"
+#include "chrome/browser/extensions/api/identity/identity_remove_cached_auth_token_function.h"
 #include "chrome/browser/extensions/api/identity/identity_signin_flow.h"
 #include "chrome/browser/extensions/api/identity/web_auth_flow.h"
 #include "chrome/browser/extensions/chrome_extension_function.h"
@@ -319,19 +320,6 @@ class IdentityGetProfileUserInfoFunction
   ExtensionFunction::ResponseAction Run() override;
 };
 
-class IdentityRemoveCachedAuthTokenFunction : public UIThreadExtensionFunction {
- public:
-  DECLARE_EXTENSION_FUNCTION("identity.removeCachedAuthToken",
-                             EXPERIMENTAL_IDENTITY_REMOVECACHEDAUTHTOKEN)
-  IdentityRemoveCachedAuthTokenFunction();
-
- protected:
-  ~IdentityRemoveCachedAuthTokenFunction() override;
-
-  // ExtensionFunction:
-  ResponseAction Run() override;
-};
-
 }  // namespace extensions
 
 #endif  // CHROME_BROWSER_EXTENSIONS_API_IDENTITY_IDENTITY_API_H_