struct UnloadedExtensionInfo -> enum UnloadedExtensionInfoReason

We don't need to keep struct UnloadedExtensionInfo.
So removing it and use enum UnloadedExtensionInfoReason instead.

TEST=Everything runs smoothly
BUG=715144

Review-Url: https://codereview.chromium.org/2839373003
Cr-Commit-Position: refs/heads/master@{#469065}
diff --git a/extensions/browser/lazy_background_task_queue.cc b/extensions/browser/lazy_background_task_queue.cc
index 7a98326..2403154 100644
--- a/extensions/browser/lazy_background_task_queue.cc
+++ b/extensions/browser/lazy_background_task_queue.cc
@@ -178,7 +178,7 @@
 void LazyBackgroundTaskQueue::OnExtensionUnloaded(
     content::BrowserContext* browser_context,
     const Extension* extension,
-    UnloadedExtensionInfo::Reason reason) {
+    UnloadedExtensionReason reason) {
   // Notify consumers that the page failed to load.
   ProcessPendingTasks(NULL, browser_context, extension);
   // If this extension is also running in an off-the-record context, notify that