Add a Content API around TracingController.

content/public/browser/trace_subscriber.h

+// 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.
+
+#ifndef CONTENT_PUBLIC_BROWSER_TRACE_SUBSCRIBER_H_
+#define CONTENT_PUBLIC_BROWSER_TRACE_SUBSCRIBER_H_
+
+#include <set>
+
+#include "base/memory/ref_counted_memory.h"
+
+namespace content {
+
+// Objects interested in receiving trace data derive from TraceSubscriber.
+// See also: trace_message_filter.h
+// See also: child_trace_message_filter.h
+class TraceSubscriber {

[Jói, 2012/03/13 10:13:51]

Since this is in the Content API, shouldn't it be exported?  Then you could get
rid of the NON_EXPORTED_BASE declaration where TraceSubscriberStdio inherits
from this.

[Jói, 2012/03/13 13:03:41]

Never mind, just realized this is pure virtual.

+ public:
+  // Called once after TraceController::EndTracingAsync.
+  virtual void OnEndTracingComplete() = 0;
+
+  // Called 0 or more times between TraceController::BeginTracing and
+  // OnEndTracingComplete. Use base::debug::TraceResultBuffer to convert one or
+  // more trace fragments to JSON.
+  virtual void OnTraceDataCollected(
+      const scoped_refptr<base::RefCountedString>& trace_fragment) = 0;
+
+  // Called once after TraceController::GetKnownCategoriesAsync.
+  virtual void OnKnownCategoriesCollected(
+      const std::set<std::string>& known_categories) {}
+
+  virtual void OnTraceBufferPercentFullReply(float percent_full) {}
+
+ protected:
+  virtual ~TraceSubscriber() {}
+};
+
+}  // namespace content
+
+#endif  // CONTENT_PUBLIC_BROWSER_TRACE_SUBSCRIBER_H_