Fix content verifier problem with content scripts (reland)

extensions/browser/content_verifier.h

Index: extensions/browser/content_verifier.h
diff --git a/extensions/browser/content_verifier.h b/extensions/browser/content_verifier.h
index 47f67c1411be6c1770eac92098a63b417af67dda..8d6f47b5c64b6c635f647911edbbdd1f63c1cce7 100644
--- a/extensions/browser/content_verifier.h
+++ b/extensions/browser/content_verifier.h
@@ -37,6 +37,13 @@ class ContentVerifierIOData;
 class ContentVerifier : public base::RefCountedThreadSafe<ContentVerifier>,
                         public ExtensionRegistryObserver {
  public:
+  class TestObserver {
+   public:
+    virtual void OnFetchComplete(const std::string& extension_id,
+                                 bool success) = 0;
+  };
+  static void SetObserverForTests(TestObserver* observer);
+
   // Takes ownership of |delegate|.
   ContentVerifier(content::BrowserContext* context,
                   ContentVerifierDelegate* delegate);