Improve memory estimate of SpdySessionPool in net/ MemoryDumpProvider.

net/http2/hpack/decoder/hpack_whole_entry_buffer.cc

Index: net/http2/hpack/decoder/hpack_whole_entry_buffer.cc
diff --git a/net/http2/hpack/decoder/hpack_whole_entry_buffer.cc b/net/http2/hpack/decoder/hpack_whole_entry_buffer.cc
index 8bb212f40aaea1a96eb983ac0cfa4ec3e0f0d897..429938fda7a2e93e0b9870a6777a29c392bbfcb8 100644
--- a/net/http2/hpack/decoder/hpack_whole_entry_buffer.cc
+++ b/net/http2/hpack/decoder/hpack_whole_entry_buffer.cc
@@ -5,6 +5,7 @@
 #include "net/http2/hpack/decoder/hpack_whole_entry_buffer.h"
 
 #include "base/logging.h"
+#include "base/trace_event/memory_usage_estimator.h"
 
 using base::StringPiece;
 
@@ -32,6 +33,11 @@ void HpackWholeEntryBuffer::BufferStringsIfUnbuffered() {
   value_.BufferStringIfUnbuffered();
 }
 
+size_t HpackWholeEntryBuffer::EstimateMemoryUsage() const {
+  return base::trace_event::EstimateMemoryUsage(name_) +
+         base::trace_event::EstimateMemoryUsage(value_);
+}
+
 void HpackWholeEntryBuffer::OnIndexedHeader(size_t index) {
   DVLOG(2) << "HpackWholeEntryBuffer::OnIndexedHeader: index=" << index;
   listener_->OnIndexedHeader(index);