Gather trace data by waiting on handles with a fixed timeout

services/tracing/collector_impl.h

Index: services/tracing/collector_impl.h
diff --git a/services/tracing/collector_impl.h b/services/tracing/collector_impl.h
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+// 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.
+
+#ifndef SERVICES_TRACING_COLLECTOR_IMPL_H_
+#define SERVICES_TRACING_COLLECTOR_IMPL_H_
+
+#include "base/macros.h"
+#include "mojo/public/cpp/bindings/binding.h"
+#include "mojo/public/cpp/bindings/string.h"
+#include "services/tracing/trace_data_sink.h"
+#include "services/tracing/tracing.mojom.h"
+
+namespace tracing {
+
+class CollectorImpl : public TraceDataCollector {
+ public:
+  CollectorImpl(mojo::InterfaceRequest<TraceDataCollector> request,
+                TraceDataSink* sink);
+  ~CollectorImpl() override;
+
+  // TryRead attempts to read a single chunk from the TraceDataCollector pipe if
+  // one is available and passes it to the TraceDataSink. Returns immediately if
+  // no chunk is available.
+  void TryRead();
+
+  // TraceDataCollectorHandle returns the handle value of the TraceDataCollector
+  // binding which can be used to wait until chunks are available.
+  mojo::Handle TraceDataCollectorHandle() const;
+
+ private:
+  // tracing::TraceDataCollector implementation.
+  void DataCollected(const mojo::String& json) override;
+
+  TraceDataSink* sink_;
+  mojo::Binding<TraceDataCollector> binding_;
+
+  DISALLOW_COPY_AND_ASSIGN(CollectorImpl);
+};
+
+}  // namespace tracing
+
+#endif  // SERVICES_TRACING_COLLECTOR_IMPL_H_