Update most ScopedObserver declarations in //chrome/browser

Bug: 998625
Change-Id: I239558c07ce10166b82a2b886ef08a1d4ede56f2
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1817333
Reviewed-by: Scott Violet <[email protected]>
Commit-Queue: Evan Stade <[email protected]>
Cr-Commit-Position: refs/heads/master@{#699035}
diff --git a/chrome/browser/autocomplete/shortcuts_extensions_manager.h b/chrome/browser/autocomplete/shortcuts_extensions_manager.h
index 4f60a5b..8f876d6 100644
--- a/chrome/browser/autocomplete/shortcuts_extensions_manager.h
+++ b/chrome/browser/autocomplete/shortcuts_extensions_manager.h
@@ -8,14 +8,11 @@
 #include "base/macros.h"
 #include "base/scoped_observer.h"
 #include "base/supports_user_data.h"
+#include "extensions/browser/extension_registry.h"
 #include "extensions/browser/extension_registry_observer.h"
 
 class Profile;
 
-namespace extensions {
-class ExtensionRegistry;
-}
-
 // This class manages the removal of shortcuts associated with an extension when
 // that extension is unloaded.
 class ShortcutsExtensionsManager
@@ -34,7 +31,7 @@
  private:
   ScopedObserver<extensions::ExtensionRegistry,
                  extensions::ExtensionRegistryObserver>
-      registry_observer_;
+      registry_observer_{this};
   Profile* profile_;
 
   DISALLOW_COPY_AND_ASSIGN(ShortcutsExtensionsManager);