initial import of Chrome's trace_event into skia framework

This patch includes a modified version of Chrome's trace_event.h, which provides
tracing macros that can easily integrate into the about://tracing framework.

Currently the macros link to a default implementation of the (narrow) tracing
class SkDefaultEventTracer which does nothing; next step will be to have Chrome
subclass the SkEventTracer with a shim that bolts Skia's trace events to its own,
allowing Skia's trace events to show up in about://tracing.

I've verified that this file builds properly, and when I added a simple scoped
TRACE_EVENT0 to SkCanvas::drawRect, along with some debug prints in the NOP
implementation of tracing, I saw what I expected printed to the screen.

BUG=skia:
R=nduca@chromium.org, reed@google.com, mtklein@google.com, bsalomon@google.com

Author: humper@google.com

Review URL: https://codereview.chromium.org/149563004

git-svn-id: http://skia.googlecode.com/svn/trunk@13256 2bbb7eff-a529-9590-31e7-b0007b416f81

1 files changed, 13 insertions, 0 deletions

diff --git a/tests/TracingTest.cpp b/tests/TracingTest.cpp
new file mode 100644
index 0000000000..730a46ce4d
--- /dev/null
+++ b/tests/TracingTest.cpp
@@ -0,0 +1,13 @@
+/*
+ * Copyright 2014 Google Inc.
+ *
+ * Use of this source code is governed by a BSD-style license that can be
+ * found in the LICENSE file.
+ */
+
+#include "SkTraceEvent.h"
+#include "Test.h"
+
+DEF_TEST(Tracing, reporter) {
+  TRACE_EVENT0("skia.testing", "just a test");
+}