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..d239aca8ecd728c690827c0b5f5ed965bc163b50 100644
--- a/net/http2/hpack/decoder/hpack_whole_entry_buffer.cc
+++ b/net/http2/hpack/decoder/hpack_whole_entry_buffer.cc
@@ -32,6 +32,10 @@ void HpackWholeEntryBuffer::BufferStringsIfUnbuffered() {
   value_.BufferStringIfUnbuffered();
 }
 
+size_t HpackWholeEntryBuffer::EstimateMemoryUsage() const {
+  return name_.BufferedLength() + value_.BufferedLength();
+}
+
 void HpackWholeEntryBuffer::OnIndexedHeader(size_t index) {
   DVLOG(2) << "HpackWholeEntryBuffer::OnIndexedHeader: index=" << index;
   listener_->OnIndexedHeader(index);