[MD Extensions] Respond with a load error when loading unpacked fails

chrome/browser/ui/webui/extensions/extension_loader_handler.h

Index: chrome/browser/ui/webui/extensions/extension_loader_handler.h
diff --git a/chrome/browser/ui/webui/extensions/extension_loader_handler.h b/chrome/browser/ui/webui/extensions/extension_loader_handler.h
index b99ad4cab4489dd9fce87398ca7c9ccb9bad8683..a379fe1cd09f0608adf9865bb8674367af690f34 100644
--- a/chrome/browser/ui/webui/extensions/extension_loader_handler.h
+++ b/chrome/browser/ui/webui/extensions/extension_loader_handler.h
@@ -11,6 +11,7 @@
 #include <string>
 #include <vector>
 
+#include "base/callback.h"
 #include "base/compiler_specific.h"
 #include "base/files/file_path.h"
 #include "base/macros.h"
@@ -37,6 +38,12 @@ class ExtensionLoaderHandler : public content::WebUIMessageHandler,
                                public ExtensionErrorReporter::Observer,
                                public content::WebContentsObserver {
  public:
+  using GetManifestErrorCallback =
+      base::Callback<void(const base::FilePath& file_path,
+                          const std::string& error,
+                          size_t line_number,
+                          const std::string& manifest)>;
+
   explicit ExtensionLoaderHandler(Profile* profile);
   ~ExtensionLoaderHandler() override;
 
@@ -46,6 +53,11 @@ class ExtensionLoaderHandler : public content::WebUIMessageHandler,
   // WebUIMessageHandler implementation.
   void RegisterMessages() override;
 
+  // TODO(devlin): Move this to developerPrivate.
+  static void GetManifestError(const std::string& error,
+                               const base::FilePath& extension_path,
+                               const GetManifestErrorCallback& callback);
+
  private:
   // Handle the 'extensionLoaderRetry' message.
   void HandleRetry(const base::ListValue* args);