[Smart Lock] Add a private API to show an error bubble anchored to the Smart Lock app window.

chrome/browser/extensions/api/easy_unlock_private/easy_unlock_private_api.h

Index: chrome/browser/extensions/api/easy_unlock_private/easy_unlock_private_api.h
diff --git a/chrome/browser/extensions/api/easy_unlock_private/easy_unlock_private_api.h b/chrome/browser/extensions/api/easy_unlock_private/easy_unlock_private_api.h
index b835bdeacdb9e1a998a9e08cd45c074882b4357c..8f366c677b28e325e11275b473b054b12734a255 100644
--- a/chrome/browser/extensions/api/easy_unlock_private/easy_unlock_private_api.h
+++ b/chrome/browser/extensions/api/easy_unlock_private/easy_unlock_private_api.h
@@ -353,6 +353,21 @@ class EasyUnlockPrivateGetConnectionInfoFunction
   DISALLOW_COPY_AND_ASSIGN(EasyUnlockPrivateGetConnectionInfoFunction);
 };
 
+class EasyUnlockPrivateShowErrorBubbleFunction : public SyncExtensionFunction {
+ public:
+  DECLARE_EXTENSION_FUNCTION("easyUnlockPrivate.showErrorBubble",
+                             EASYUNLOCKPRIVATE_SHOWERRORBUBBLE)
+  EasyUnlockPrivateShowErrorBubbleFunction();
+
+ private:
+  ~EasyUnlockPrivateShowErrorBubbleFunction() override;
+
+  // SyncExtensionFunction:
+  bool RunSync() override;
+
+  DISALLOW_COPY_AND_ASSIGN(EasyUnlockPrivateShowErrorBubbleFunction);
+};
+
 }  // namespace api
 }  // namespace extensions