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/process_manager.h b/extensions/browser/process_manager.h
index 7d6e422..209aff7 100644
--- a/extensions/browser/process_manager.h
+++ b/extensions/browser/process_manager.h
@@ -211,7 +211,7 @@
                          const Extension* extension) override;
   void OnExtensionUnloaded(content::BrowserContext* browser_context,
                            const Extension* extension,
-                           UnloadedExtensionInfo::Reason reason) override;
+                           UnloadedExtensionReason reason) override;
 
   // Extra information we keep for each extension's background page.
   struct BackgroundPageData;