implement SetWatchEvent and WaitForEvent for trace-based-tests

base/test/trace_event_analyzer_unittest.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 "base/bind.h"
 #include "base/debug/trace_event_unittest.h"
 #include "base/test/trace_event_analyzer.h"
 #include "testing/gmock/include/gmock/gmock.h"
 #include "testing/gtest/include/gtest/gtest.h"
 
 namespace trace_analyzer {
 
 namespace {
 
 class TraceEventAnalyzerTest : public testing::Test {
  public:
   void ManualSetUp();
   void OnTraceDataCollected(
       const scoped_refptr<base::RefCountedString>& json_events_str);
   void BeginTracing();
   void EndTracing();
 
   base::debug::TraceResultBuffer::SimpleOutput output_;
   base::debug::TraceResultBuffer buffer_;
 };
 
 void TraceEventAnalyzerTest::ManualSetUp() {
   base::debug::TraceLog::Resurrect();
-  base::debug::TraceLog* tracelog = base::debug::TraceLog::GetInstance();
-  ASSERT_TRUE(tracelog);
-  tracelog->SetOutputCallback(
-    base::Bind(&TraceEventAnalyzerTest::OnTraceDataCollected,
-               base::Unretained(this)));
+  ASSERT_TRUE(base::debug::TraceLog::GetInstance());
   buffer_.SetOutputCallback(output_.GetCallback());
   output_.json_output.clear();
 }
 
 void TraceEventAnalyzerTest::OnTraceDataCollected(
     const scoped_refptr<base::RefCountedString>& json_events_str) {
   buffer_.AddFragment(json_events_str->data());
 }
 
 void TraceEventAnalyzerTest::BeginTracing() {
   output_.json_output.clear();
   buffer_.Start();
   base::debug::TraceLog::GetInstance()->SetEnabled(true);
 }
 
 void TraceEventAnalyzerTest::EndTracing() {
   base::debug::TraceLog::GetInstance()->SetEnabled(false);
+  base::debug::TraceLog::GetInstance()->Flush(
+      base::Bind(&TraceEventAnalyzerTest::OnTraceDataCollected,
+                 base::Unretained(this)));
   buffer_.Finish();
 }
 
 }  // namespace
 
 TEST_F(TraceEventAnalyzerTest, NoEvents) {
   ManualSetUp();
 
   // Create an empty JSON event string:
   buffer_.Start();
@@ skipping 758 matching lines @@
   EXPECT_EQ(num_events, CountMatches(event_ptrs, Query::Bool(true)));
   EXPECT_EQ(num_events - 1, CountMatches(event_ptrs, Query::Bool(true),
                                          1, num_events));
   EXPECT_EQ(1u, CountMatches(event_ptrs, query_one));
   EXPECT_EQ(num_events - 1, CountMatches(event_ptrs, !query_one));
   EXPECT_EQ(num_named, CountMatches(event_ptrs, query_named));
 }
 
 
 }  // namespace trace_analyzer