Settings reset prompt: Fix crash when fetching default settings.

When the Chrome installation has a brand code, the SettingsResetPromptModel may try to fetch default settings over the network. If the fetch fails, the ProfileResetter is passed a null pointer and any attempt to reset a setting will crash.

BUG=716372

Review-Url: https://codereview.chromium.org/2852883002
Cr-Commit-Position: refs/heads/master@{#468270}

chrome/browser/safe_browsing/settings_reset_prompt/settings_reset_prompt_model.cc

@@ -136,7 +136,13 @@ void DefaultSettingsFetcher::OnSettingsFetched() {
   DCHECK(config_fetcher_);
   DCHECK(!config_fetcher_->IsActive());
 
-  PostCallbackAndDeleteSelf(config_fetcher_->GetSettings());
+  std::unique_ptr<BrandcodedDefaultSettings> settings(
+      config_fetcher_->GetSettings());
+  // Use default settings if fetching of BrandcodedDefaultSettings fails.
+  if (!settings)
+    settings.reset(new BrandcodedDefaultSettings());
+
+  PostCallbackAndDeleteSelf(std::move(settings));
 }
 
 void DefaultSettingsFetcher::PostCallbackAndDeleteSelf(