Revert of tracing v2: Introduce TraceBufferWriter

components/tracing/core/scattered_stream_writer.cc

Index: components/tracing/core/scattered_stream_writer.cc
diff --git a/components/tracing/core/scattered_stream_writer.cc b/components/tracing/core/scattered_stream_writer.cc
index 37ca5b355075094c4f66a13607f7267d2998a86d..73e2a36ae20ebf7e829555caecb2951e17f8b6c1 100644
--- a/components/tracing/core/scattered_stream_writer.cc
+++ b/components/tracing/core/scattered_stream_writer.cc
@@ -12,8 +12,6 @@
 
 namespace tracing {
 namespace v2 {
-
-ScatteredStreamWriter::Delegate::~Delegate() {}
 
 ScatteredStreamWriter::ScatteredStreamWriter(Delegate* delegate)
     : delegate_(delegate),
@@ -64,7 +62,7 @@
 // TODO(primiano): perf optimization: I suspect that at the end this will always
 // be called with |size| == 4, in which case we might just hardcode it.
 ContiguousMemoryRange ScatteredStreamWriter::ReserveBytes(size_t size) {
-  // Assume the reservations are always < kChunkSize.
+  // Assume the reservations are always < TraceRingBuffer::Chunk::kSize.
   if (write_ptr_ + size > cur_range_.end) {
     Extend();
     DCHECK_LE(write_ptr_ + size, cur_range_.end);