DO NOT SUBMIT: In-process tracing for debugging tests

base/debug/in_process_tracing.cc

+// Copyright (c) 2013 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/in_process_tracing.h"
+#include "base/debug/trace_event.h"
+#include "base/memory/ref_counted.h"
+#include "base/memory/singleton.h"
+
+namespace {
+
+class InProcessTraceController {
+ public:
+  static InProcessTraceController* GetInstance() {
+    return Singleton<InProcessTraceController>::get();
+  }
+
+  InProcessTraceController() {}
+  virtual ~InProcessTraceController() {}
+
+  bool BeginTracing(const std::string& category_patterns) {
+    base::debug::TraceLog::GetInstance()->SetEnabled(
+        base::debug::CategoryFilter(category_patterns),
+        base::debug::TraceLog::RECORD_UNTIL_FULL);
+    return true;
+  }
+
+  void OnTraceDataCollected(
+      const scoped_refptr<base::RefCountedString>& events_str,
+      bool has_more_events) {
+    trace_buffer_.AddFragment(events_str->data());
+  }
+
+  bool EndTracing(std::string* json_trace_output) {
+    using namespace base::debug;
+
+    base::debug::TraceLog::GetInstance()->SetDisabled();
+
+    TraceResultBuffer::SimpleOutput output;
+    trace_buffer_.SetOutputCallback(output.GetCallback());
+
+    trace_buffer_.Start();
+
+    base::debug::TraceLog::GetInstance()->Flush(
+        base::Bind(&InProcessTraceController::OnTraceDataCollected,
+                   base::Unretained(this)));
+
+    trace_buffer_.Finish();
+    trace_buffer_.SetOutputCallback(TraceResultBuffer::OutputCallback());
+    *json_trace_output = output.json_output;
+    return true;
+  }
+
+ private:
+  friend struct DefaultSingletonTraits<InProcessTraceController>;
+
+  // For collecting trace data asynchronously.
+  base::debug::TraceResultBuffer trace_buffer_;
+
+  DISALLOW_COPY_AND_ASSIGN(InProcessTraceController);
+};
+
+}  // namespace
+
+namespace tracing {
+
+bool BeginTracing(const std::string& category_patterns) {
+  return InProcessTraceController::GetInstance()->BeginTracing(
+      category_patterns);
+}
+
+bool EndTracing(std::string* json_trace_output) {
+  return InProcessTraceController::GetInstance()->EndTracing(json_trace_output);
+}
+
+}  // namespace tracing