Telemetry / Devtools TraceHandler: exposes tracing via dev tools.

content/browser/debugger/devtools_trace_handler.cc

Index: content/browser/debugger/devtools_trace_handler.cc
diff --git a/content/browser/debugger/devtools_trace_handler.cc b/content/browser/debugger/devtools_trace_handler.cc
new file mode 100644
index 0000000000000000000000000000000000000000..b3dd8a1e17341e52dce6f2c495470a3db9d96448
--- /dev/null
+++ b/content/browser/debugger/devtools_trace_handler.cc
@@ -0,0 +1,53 @@
+// 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 "content/browser/debugger/devtools_trace_handler.h"
+
+#include "base/bind.h"
+#include "base/callback.h"
+#include "base/location.h"
+#include "content/public/browser/browser_thread.h"
+#include "content/public/browser/trace_controller.h"
+#include "content/public/browser/trace_subscriber.h"
+
+namespace content {
+
+DevToolsTraceHandler::DevToolsTraceHandler()
+    : has_completed_(false) {
+}
+
+DevToolsTraceHandler::~DevToolsTraceHandler() {
+}
+
+void DevToolsTraceHandler::BeginTracing(const std::string& categories) {
+  TraceController::GetInstance()->BeginTracing(this, categories);
+}
+
+void DevToolsTraceHandler::EndTracingAsync() {
+  TraceController::GetInstance()->EndTracingAsync(this);
+}
+
+bool DevToolsTraceHandler::has_completed() const {
+  return has_completed_;
+}
+
+void DevToolsTraceHandler::OnEndTracingComplete() {
+  has_completed_ = true;
+}
+
+void DevToolsTraceHandler::OnTraceDataCollected(
+    const scoped_refptr<base::RefCountedString>& trace_fragment) {
+  if (!buffer_.empty())
+    buffer_.append(",");
+  buffer_.append(trace_fragment->data());
+}
+
+std::string DevToolsTraceHandler::GetAndResetTrace() {
+  std::string ret(buffer_);
+  buffer_.clear();
+  has_completed_ = false;
+  return ret;
+}
+
+}  // namespace content