[Autofill] Exchange bare pointer with weak pointer for callbacks.

Change-Id: I9b1467d5f34d9381c8f944009b8f7511063fa30e
Bug: 1150004, 1148749
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2544706
Commit-Queue: Matthias Körber <koerber@google.com>
Reviewed-by: Christoph Schwering <schwering@google.com>
Cr-Commit-Position: refs/heads/master@{#828642}

components/autofill/core/browser/ui/region_combobox_model.cc

@@ -34,7 +34,7 @@ void RegionComboboxModel::LoadRegionData(const std::string& country_code,
   region_data_loader_->LoadRegionData(
       country_code,
       base::BindRepeating(&RegionComboboxModel::OnRegionDataLoaded,
-                          base::Unretained(this)),
+                          weak_factory_.GetWeakPtr()),
       timeout_ms);
 }
 

components/autofill/core/browser/ui/region_combobox_model.h

@@ -72,6 +72,9 @@ class RegionComboboxModel : public ui::ComboboxModel {
   // To be called when the data for the given country code was loaded.
   base::ObserverList<ui::ComboboxModelObserver> observers_;
 
+  // Weak pointer factory.
+  base::WeakPtrFactory<RegionComboboxModel> weak_factory_{this};
+
   DISALLOW_COPY_AND_ASSIGN(RegionComboboxModel);
 };