Enable tracing in SkyShell

sky/shell/tracing_controller.cc

Index: sky/shell/tracing_controller.cc
diff --git a/sky/shell/tracing_controller.cc b/sky/shell/tracing_controller.cc
new file mode 100644
index 0000000000000000000000000000000000000000..e22e1a3866b7e0bf2557201c49a702ed3f38db07
--- /dev/null
+++ b/sky/shell/tracing_controller.cc
@@ -0,0 +1,70 @@
+// Copyright 2015 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 "sky/shell/tracing_controller.h"
+
+#include "base/android/jni_android.h"
+#include "base/android/jni_string.h"
+#include "base/files/file_util.h"
+#include "base/macros.h"
+#include "base/trace_event/trace_event.h"
+#include "jni/TracingController_jni.h"
+
+namespace sky {
+namespace shell {
+namespace {
+
+const char kStart[] = "{\"traceEvents\":[";
+const char kEnd[] = "]}";
+
+static FILE* g_file = NULL;
+
+void Write(const std::string& data) {
+  ignore_result(fwrite(data.data(), data.length(), 1, g_file));
+}
+
+void HandleChunk(const scoped_refptr<base::RefCountedString>& chunk,
+                 bool has_more_events) {
+  Write(chunk->data());
+  if (has_more_events)
+    Write(",");
+
+  if (!has_more_events) {
+    Write(kEnd);
+    base::CloseFile(g_file);
+    g_file = NULL;
+
+    LOG(INFO) << "Trace complete";
+  }
+}
+
+}  // namespace
+
+static void StartTracing(JNIEnv* env, jclass clazz) {
+  LOG(INFO) << "Starting trace";
+
+  base::trace_event::TraceLog::GetInstance()->SetEnabled(
+      base::trace_event::CategoryFilter("*"),
+      base::trace_event::TraceLog::RECORDING_MODE,
+      base::trace_event::TraceOptions(base::trace_event::RECORD_UNTIL_FULL));
+}
+
+static void StopTracing(JNIEnv* env, jclass clazz, jstring path) {
+  base::trace_event::TraceLog::GetInstance()->SetDisabled();
+
+  base::FilePath file_path(base::android::ConvertJavaStringToUTF8(env, path));
+  g_file = base::OpenFile(file_path, "w");
+  CHECK(g_file) << "Failed to open file " << file_path.LossyDisplayName();
+
+  LOG(INFO) << "Saving trace to " << file_path.LossyDisplayName();
+  Write(kStart);
+  base::trace_event::TraceLog::GetInstance()->Flush(base::Bind(&HandleChunk));
+}
+
+bool RegisterTracingController(JNIEnv* env) {
+  return RegisterNativesImpl(env);
+}
+
+}  // namespace shell
+}  // namespace sky