Remove BindStateHolder and have Bind() return a Callback<> object directly.

base/test/trace_event_analyzer_unittest.cc

Index: base/test/trace_event_analyzer_unittest.cc
diff --git a/base/test/trace_event_analyzer_unittest.cc b/base/test/trace_event_analyzer_unittest.cc
index 96f804534f817f8640d261f8f2bca4859697bb40..1c9fafe6ea405481a47ad059630005f188589d54 100644
--- a/base/test/trace_event_analyzer_unittest.cc
+++ b/base/test/trace_event_analyzer_unittest.cc
@@ -15,7 +15,8 @@ class TraceEventAnalyzerTest : public testing::Test {
  public:
   void ManualSetUp();
   void OnTraceDataCollected(
-      scoped_refptr<base::debug::TraceLog::RefCountedString> json_events_str);
+      const scoped_refptr<base::debug::TraceLog::RefCountedString>&
+          json_events_str);
   void BeginTracing();
   void EndTracing();
 
@@ -35,7 +36,8 @@ void TraceEventAnalyzerTest::ManualSetUp() {
 }
 
 void TraceEventAnalyzerTest::OnTraceDataCollected(
-    scoped_refptr<base::debug::TraceLog::RefCountedString> json_events_str) {
+    const scoped_refptr<base::debug::TraceLog::RefCountedString>&
+        json_events_str) {
   buffer_.AddFragment(json_events_str->data);
 }
 
@@ -609,4 +611,3 @@ TEST_F(TraceEventAnalyzerTest, RateStats) {
 
 
 }  // namespace trace_analyzer
-