Add a |scope| argument to TRACE_EVENT_INSTANT* and require its presence.

chrome/test/base/tracing_browsertest.cc

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "chrome/test/base/tracing.h"
 
 #include "base/debug/trace_event.h"
 #include "base/message_loop.h"
 #include "base/run_loop.h"
 #include "chrome/browser/ui/browser.h"
@@ skipping 21 matching lines @@
   void ExecuteJavascriptOnCurrentTab() {
     content::RenderViewHost* rvh = browser()->tab_strip_model()->
         GetActiveWebContents()->GetRenderViewHost();
     ASSERT_TRUE(rvh);
     ASSERT_TRUE(content::ExecuteScript(rvh, ";"));
   }
 };
 
 void AddEvents(int num) {
   for (int i = 0; i < num; ++i)
-    TRACE_EVENT_INSTANT0(g_category, g_event);
+    TRACE_EVENT_INSTANT0(g_category, g_event, TRACE_EVENT_SCOPE_THREAD);
 }
 
 IN_PROC_BROWSER_TEST_F(TracingBrowserTest, BeginTracingWithWatch) {
   base::TimeDelta no_timeout;
   base::TimeDelta short_timeout = base::TimeDelta::FromMilliseconds(5);
   std::string json_events;
 
   // One event before wait.
   ASSERT_TRUE(BeginTracingWithWatch(g_category, g_category, g_event, 1));
   AddEvents(1);
@@ skipping 43 matching lines @@
       NEW_FOREGROUND_TAB, ui_test_utils::BROWSER_TEST_WAIT_FOR_NAVIGATION);
   ASSERT_NO_FATAL_FAILURE(ExecuteJavascriptOnCurrentTab());
   ui_test_utils::NavigateToURLWithDisposition(browser(), url2,
       NEW_FOREGROUND_TAB, ui_test_utils::BROWSER_TEST_WAIT_FOR_NAVIGATION);
   ASSERT_NO_FATAL_FAILURE(ExecuteJavascriptOnCurrentTab());
   EXPECT_TRUE(WaitForWatchEvent(no_timeout));
   ASSERT_TRUE(EndTracing(&json_events));
 }
 
 }  // namespace