arc: enable Android tracing from chrome://tracing in dev mode

components/arc/common/trace.mojom

Index: components/arc/common/trace.mojom
diff --git a/components/arc/common/trace.mojom b/components/arc/common/trace.mojom
new file mode 100644
index 0000000000000000000000000000000000000000..96ab2c38e755e7c93871730de80b7421639c3cf4
--- /dev/null
+++ b/components/arc/common/trace.mojom
@@ -0,0 +1,18 @@
+// Copyright 2017 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.
+
+// Next MinVersion: 1
+
+module arc.mojom;
+
+interface TraceInstance {
+  // Queries available tracing categories in the container.
+  QueryAvailableCategories@0() => (array<string> categories);
+
+  // Starts tracing in the container with the given categories.
+  StartTracing@1(array<string> categories) => (bool success);
+
+  // Stops tracing in the container.
+  StopTracing@2() => (bool success);
+};