[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 7192dd15bef1d321c47b1bb97d8b94a624e09eeb..461509d00b49ac8f4f5958398d1618658e7c79a8 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
@@ -347,6 +347,21 @@ class EasyUnlockPrivateGetUserImageFunction : public SyncExtensionFunction {
   DISALLOW_COPY_AND_ASSIGN(EasyUnlockPrivateGetUserImageFunction);
 };
 
+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