Added support to trace_event for passing static string arguments without copy

base/debug/trace_event_unittest.cc

 // Copyright (c) 2011 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 "base/debug/trace_event.h"
 
 #include "base/bind.h"
 #include "base/command_line.h"
 #include "base/json/json_reader.h"
 #include "base/json/json_writer.h"
+#include "base/memory/ref_counted_memory.h"
 #include "base/memory/scoped_ptr.h"
 #include "base/process_util.h"
 #include "base/stringprintf.h"
 #include "base/synchronization/waitable_event.h"
 #include "base/threading/thread.h"
 #include "base/values.h"
 #include "testing/gmock/include/gmock/gmock.h"
 #include "testing/gtest/include/gtest/gtest.h"
 
 namespace base {
@@ skipping 434 matching lines @@
   EXPECT_NOT_FIND_BE_("3thresholdlong2");
 
   EXPECT_FIND_BE_("nonthreshold4");
   EXPECT_FIND_BE_("4threshold100");
   EXPECT_FIND_BE_("4threshold1000");
   EXPECT_FIND_BE_("4threshold10000");
   EXPECT_NOT_FIND_BE_("4thresholdlong1");
   EXPECT_NOT_FIND_BE_("4thresholdlong2");
 }
 
+// Test that static strings are not copied.
+TEST_F(TraceEventTestFixture, StaticStringVsString) {
+  ManualTestSetUp();
+  TraceLog* tracer = TraceLog::GetInstance();
+  // Make sure old events are flushed:
+  tracer->SetEnabled(false);
+  EXPECT_EQ(0u, tracer->GetEventsSize());
+
+  {
+    // Test that normal string arguments are copied.
+    tracer->SetEnabled(true);
+    TRACE_EVENT2("cat", "name1", "arg1", "argval", "arg2", "argval");
+    size_t num_events = tracer->GetEventsSize();
+    EXPECT_GT(num_events, 0u);
+    const TraceEvent& event = tracer->GetEventAt(num_events - 1);
+    EXPECT_STREQ("name1", event.name());
+    EXPECT_TRUE(event.parameter_copy_storage() != NULL);
+    EXPECT_GT(event.parameter_copy_storage()->size(), 0u);
+    tracer->SetEnabled(false);
+  }
+
+  {
+    // Test that static string arguments are not copied.
+    tracer->SetEnabled(true);
+    TRACE_EVENT2("cat", "name2", "arg1", TRACE_STATIC_STR("argval"),
+                 "arg2", TRACE_STATIC_STR("argval"));
+    size_t num_events = tracer->GetEventsSize();
+    EXPECT_GT(num_events, 0u);
+    const TraceEvent& event = tracer->GetEventAt(num_events - 1);
+    EXPECT_STREQ("name2", event.name());
+    EXPECT_TRUE(event.parameter_copy_storage() == NULL);
+    tracer->SetEnabled(false);
+  }
+}
+
 // Test that data sent from other threads is gathered
 TEST_F(TraceEventTestFixture, DataCapturedOnThread) {
   ManualTestSetUp();
   TraceLog::GetInstance()->SetEnabled(true);
 
   Thread thread("1");
   WaitableEvent task_complete_event(false, false);
   thread.Start();
 
   thread.message_loop()->PostTask(
@@ skipping 235 matching lines @@
 
   std::string s;
   EXPECT_TRUE(entry3->GetString("args.arg1", &s));
   EXPECT_EQ("val1", s);
   EXPECT_TRUE(entry3->GetString("args.arg2", &s));
   EXPECT_EQ("val2", s);
 }
 
 }  // namespace debug
 }  // namespace base