base::RefCounted now DCHECKs when referenced from multiple threads.

components/url_matcher/url_matcher.h

Index: components/url_matcher/url_matcher.h
diff --git a/components/url_matcher/url_matcher.h b/components/url_matcher/url_matcher.h
index d8fe0327854ea1da5c3fd46d5e55ada51fdbbbea..f5d7e01c816ef70459600540a8e45acf5683ab88 100644
--- a/components/url_matcher/url_matcher.h
+++ b/components/url_matcher/url_matcher.h
@@ -303,8 +303,9 @@ class URL_MATCHER_EXPORT URLMatcherPortFilter {
 
 // This class represents a set of conditions that all need to match on a
 // given URL in order to be considered a match.
+// TODO(mgiuca): Avoid using UnsafeRefCounted. http://crbug.com/469952.
 class URL_MATCHER_EXPORT URLMatcherConditionSet
-    : public base::RefCounted<URLMatcherConditionSet> {
+    : public base::UnsafeRefCounted<URLMatcherConditionSet> {
  public:
   typedef int ID;
   typedef std::set<URLMatcherCondition> Conditions;
@@ -343,7 +344,7 @@ class URL_MATCHER_EXPORT URLMatcherConditionSet
                const std::string& url_for_component_searches) const;
 
  private:
-  friend class base::RefCounted<URLMatcherConditionSet>;
+  friend class base::UnsafeRefCounted<URLMatcherConditionSet>;
   ~URLMatcherConditionSet();
   ID id_;
   Conditions conditions_;