plumbing for skia trace events into Chrome's about://tracing framework

skia/ext/event_tracer_impl.cc

+// Copyright (c) 2014 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/trace_event.h"
+#include "skia/ext/event_tracer_impl.h"
+#include "third_party/skia/include/utils/SkEventTracer.h"
+
+namespace skia {
+
+class SkChromiumEventTracer: public SkEventTracer {
+  virtual const uint8_t* getCategoryGroupEnabled(const char* name);
+  virtual const char* getCategoryGroupName(
+      const uint8_t* categoryEnabledFlag);
+  virtual SkEventTracer::Handle
+    addTraceEvent(char phase,
+                  const uint8_t* categoryEnabledFlag,
+                  const char* name,
+                  uint64_t id,
+                  int32_t numArgs,
+                  const char** argNames,
+                  const uint8_t* argTypes,
+                  const uint64_t* argValues,
+                  uint8_t flags);
+  virtual void
+    updateTraceEventDuration(const uint8_t* categoryEnabledFlag,
+                             const char *name,
+                             SkEventTracer::Handle handle);
+};
+
+const uint8_t*
+  SkChromiumEventTracer::getCategoryGroupEnabled(const char* name) {
+    return TRACE_EVENT_API_GET_CATEGORY_GROUP_ENABLED(name);
+}
+
+const char* SkChromiumEventTracer::getCategoryGroupName(
+      const uint8_t* categoryEnabledFlag) {
+  return base::debug::TraceLog::GetCategoryGroupName(
+      categoryEnabledFlag);
+}
+
+SkEventTracer::Handle
+    SkChromiumEventTracer::addTraceEvent(char phase,
+                                         const uint8_t* categoryEnabledFlag,
+                                         const char* name,
+                                         uint64_t id,
+                                         int32_t numArgs,
+                                         const char** argNames,
+                                         const uint8_t* argTypes,
+                                         const uint64_t* argValues,
+                                         uint8_t flags) {
+      base::debug::TraceEventHandle handle = TRACE_EVENT_API_ADD_TRACE_EVENT(
+          phase, categoryEnabledFlag, name, id, numArgs, argNames,
+          argTypes, (const long long unsigned int*) argValues, NULL, flags);
+      SkEventTracer::Handle result;
+      memcpy(&result, &handle, sizeof(result));
+      return result;
+}
+
+void
+    SkChromiumEventTracer::updateTraceEventDuration(
+        const uint8_t* categoryEnabledFlag,
+        const char *name,
+        SkEventTracer::Handle handle) {
+      base::debug::TraceEventHandle traceEventHandle;
+      memcpy(&traceEventHandle, &handle, sizeof(handle));
+      TRACE_EVENT_API_UPDATE_TRACE_EVENT_DURATION(
+          categoryEnabledFlag, name, traceEventHandle);
+}
+
+}  // namespace skia
+
+
+void InitSkiaEventTracer() {
+  // Initialize the binding to Skia's tracing events. Skia will

[nduca, 2014/02/04 20:01:38]

lgtm

should you dcheck against multiple initialization?

+  // take ownership of and clean up the memory allocated here.
+  SkEventTracer::SetInstance(new skia::SkChromiumEventTracer());
+}