Resume encryption migration immediately if the previous migration is incomplete.

chrome/browser/chromeos/login/existing_user_controller.h

Index: chrome/browser/chromeos/login/existing_user_controller.h
diff --git a/chrome/browser/chromeos/login/existing_user_controller.h b/chrome/browser/chromeos/login/existing_user_controller.h
index 9afa87da96b3134d52b37085e8b0aac8f75994ad..32f8a497364c3e69c7bb2354b48da675ea897c42 100644
--- a/chrome/browser/chromeos/login/existing_user_controller.h
+++ b/chrome/browser/chromeos/login/existing_user_controller.h
@@ -163,7 +163,8 @@ class ExistingUserController
   void OnAuthSuccess(const UserContext& user_context) override;
   void OnOffTheRecordAuthSuccess() override;
   void OnPasswordChangeDetected() override;
-  void OnOldEncryptionDetected(const UserContext& user_context) override;
+  void OnOldEncryptionDetected(const UserContext& user_context,
+                               bool has_incomplete_migration) override;
   void WhiteListCheckFailed(const std::string& email) override;
   void PolicyLoadFailed() override;
   void SetAuthFlowOffline(bool offline) override;
@@ -208,7 +209,8 @@ class ExistingUserController
   void ShowKioskAutolaunchScreen();
 
   // Shows "filesystem encryption migration" screen.
-  void ShowEncryptionMigrationScreen(const UserContext& user_context);
+  void ShowEncryptionMigrationScreen(const UserContext& user_context,
+                                     bool has_incomplete_migration);
 
   // Shows "critical TPM error" screen.
   void ShowTPMError();