Revert of tracing v2: Introduce TraceBufferWriter

components/tracing/core/proto_zero_message.h

Index: components/tracing/core/proto_zero_message.h
diff --git a/components/tracing/core/proto_zero_message.h b/components/tracing/core/proto_zero_message.h
index bbc21cacbb8e76098a160ec6a21748a876929eb9..d7fe1d4270e5a99474e940091f39dd69ac5ee4bf 100644
--- a/components/tracing/core/proto_zero_message.h
+++ b/components/tracing/core/proto_zero_message.h
@@ -29,8 +29,6 @@
 // performance. None of the methods require any dynamic memory allocation.
 class TRACING_EXPORT ProtoZeroMessage {
  public:
-  ProtoZeroMessage();
-
   // Clears up the state, allowing the message to be reused as a fresh one.
   void Reset(ScatteredStreamWriter*);
 
@@ -61,6 +59,8 @@
 #endif
 
  protected:
+  ProtoZeroMessage();
+
   void AppendVarIntU64(uint32_t field_id, uint64_t value);
   void AppendVarIntU32(uint32_t field_id, uint32_t value);
   void AppendFloat(uint32_t field_id, float value);