Use ThreadChecker rather than DCHECK_CURRENTLY_ON.

components/content_settings/core/browser/content_settings_observable_provider.cc

Index: components/content_settings/core/browser/content_settings_observable_provider.cc
diff --git a/components/content_settings/core/browser/content_settings_observable_provider.cc b/components/content_settings/core/browser/content_settings_observable_provider.cc
index 9e82fbe66000452cab8ca1de725bebf6a583c9fc..edda022d3c47e14084671d31a8ee208cce7648c1 100644
--- a/components/content_settings/core/browser/content_settings_observable_provider.cc
+++ b/components/content_settings/core/browser/content_settings_observable_provider.cc
@@ -42,4 +42,8 @@ void ObservableProvider::RemoveAllObservers() {
   observer_list_.Clear();
 }
 
+bool ObservableProvider::CalledOnValidThread() {
+  return thread_checker_.CalledOnValidThread();
+}
+
 }  // namespace content_settings