Improve memory estimate of SpdySessionPool in net/ MemoryDumpProvider.

net/spdy/http2_frame_decoder_adapter.cc

Index: net/spdy/http2_frame_decoder_adapter.cc
diff --git a/net/spdy/http2_frame_decoder_adapter.cc b/net/spdy/http2_frame_decoder_adapter.cc
index 8c34b694485c8f823106fe719e560111ee0be494..d76e02d9d8385d709c26091d2824bc5cd63ac176 100644
--- a/net/spdy/http2_frame_decoder_adapter.cc
+++ b/net/spdy/http2_frame_decoder_adapter.cc
@@ -20,6 +20,7 @@
 #include "base/optional.h"
 #include "base/strings/string_piece.h"
 #include "base/sys_byteorder.h"
+#include "base/trace_event/memory_usage_estimator.h"
 #include "net/http2/decoder/decode_buffer.h"
 #include "net/http2/decoder/decode_status.h"
 #include "net/http2/decoder/http2_frame_decoder.h"
@@ -143,6 +144,12 @@ class Http2DecoderAdapter : public SpdyFramerDecoderAdapter,
     return latched_probable_http_response_;
   }
 
+  size_t EstimateMemoryUsage() const override {
+    // Skip |frame_decoder_|, |frame_header_| and |hpack_first_frame_header_| as
+    // they don't allocate.
+    return base::trace_event::EstimateMemoryUsage(alt_svc_origin_) +
+           base::trace_event::EstimateMemoryUsage(alt_svc_value_);
+  }
   // ===========================================================================
   // Implementations of the methods declared by Http2FrameDecoderListener.