Tracing v2: wire up stubs generated by the protozero protoc plugin

components/tracing/core/trace_buffer_writer.h

 // Copyright 2016 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 COMPONENTS_TRACING_CORE_TRACE_BUFFER_WRITER_H_
 #define COMPONENTS_TRACING_CORE_TRACE_BUFFER_WRITER_H_
 
 #include "base/macros.h"
 #include "components/tracing/core/proto_zero_message.h"
 #include "components/tracing/core/proto_zero_message_handle.h"
 #include "components/tracing/core/scattered_stream_writer.h"
 #include "components/tracing/core/trace_ring_buffer.h"
 #include "components/tracing/tracing_export.h"
 
+// Fwd declaration from the generated components/tracing/proto/event.pbzero.h.
+namespace pbzero {
 namespace tracing {
+namespace proto {
+class Event;
+}  // namespace proto
+}  // namespace tracing
+}  // namespace pbzero
 
-// TODO(primiano): in next CL the Event class will just come from the C++
-// header generated by the ProtoZero plugin.
-namespace proto {
-class Event : public v2::ProtoZeroMessage {};
-}
-
+namespace tracing {
 namespace v2 {
 
-using TraceEventHandle = ProtoZeroMessageHandle<::tracing::proto::Event>;
+using TraceEventHandle = ProtoZeroMessageHandle<pbzero::tracing::proto::Event>;
 
 // This class is the entry-point to add events to the TraceRingBuffer.
 // It acts as a glue layer between the protobuf classes (ProtoZeroMessage) and
 // the chunked trace ring buffer (TraceRingBuffer). This class is deliberately
 // NOT thread safe. The expected design is that each thread owns an instance of
 // TraceBufferWriter and that trace events produced on one thread are not passed
 // to other threads.
 class TRACING_EXPORT TraceBufferWriter
     : public ScatteredStreamWriter::Delegate {
  public:
@@ skipping 56 matching lines @@
   // headers for the stub classes and reduce build time.
   ProtoZeroMessage event_;
 
   DISALLOW_COPY_AND_ASSIGN(TraceBufferWriter);
 };
 
 }  // namespace v2
 }  // namespace tracing
 
 #endif  // COMPONENTS_TRACING_CORE_TRACE_BUFFER_WRITER_H_