fix: [extensions] load extensions on the IO thread (#21811)

shell/browser/extensions/atom_extension_loader.cc

@@ -4,6 +4,8 @@
 
 #include "shell/browser/extensions/atom_extension_loader.h"
 
+#include <utility>
+
 #include "base/auto_reset.h"
 #include "base/bind.h"
 #include "base/files/file_path.h"
@@ -66,16 +68,14 @@ AtomExtensionLoader::AtomExtensionLoader(
 
 AtomExtensionLoader::~AtomExtensionLoader() = default;
 
-const Extension* AtomExtensionLoader::LoadExtension(
-    const base::FilePath& extension_dir) {
-  // TODO(nornagon): load extensions asynchronously on
-  // GetExtensionFileTaskRunner()
-  base::ScopedAllowBlockingForTesting allow_blocking;
-  scoped_refptr<const Extension> extension = LoadUnpacked(extension_dir);
-  if (extension)
-    extension_registrar_.AddExtension(extension);
-
-  return extension.get();
+void AtomExtensionLoader::LoadExtension(
+    const base::FilePath& extension_dir,
+    base::OnceCallback<void(const Extension*)> loaded) {
+  base::PostTaskAndReplyWithResult(
+      GetExtensionFileTaskRunner().get(), FROM_HERE,
+      base::BindOnce(&LoadUnpacked, extension_dir),
+      base::BindOnce(&AtomExtensionLoader::FinishExtensionLoad,
+                     weak_factory_.GetWeakPtr(), std::move(loaded)));
 }
 
 void AtomExtensionLoader::ReloadExtension(const ExtensionId& extension_id) {
@@ -100,6 +100,15 @@ void AtomExtensionLoader::UnloadExtension(
   extension_registrar_.RemoveExtension(extension_id, reason);
 }
 
+void AtomExtensionLoader::FinishExtensionLoad(
+    base::OnceCallback<void(const Extension*)> done,
+    scoped_refptr<const Extension> extension) {
+  if (extension) {
+    extension_registrar_.AddExtension(extension);
+  }
+  std::move(done).Run(extension.get());
+}
+
 void AtomExtensionLoader::FinishExtensionReload(
     const ExtensionId& old_extension_id,
     scoped_refptr<const Extension> extension) {