Improve memory estimate of SpdySessionPool in net/ MemoryDumpProvider.

net/spdy/spdy_header_block.cc

Index: net/spdy/spdy_header_block.cc
diff --git a/net/spdy/spdy_header_block.cc b/net/spdy/spdy_header_block.cc
index 6cbd6ba645c4585a3126099322effb3f9525c968..a51532cf015c5777e21661879dcd86fbfd3e7856 100644
--- a/net/spdy/spdy_header_block.cc
+++ b/net/spdy/spdy_header_block.cc
@@ -15,6 +15,7 @@
 #include "net/base/arena.h"
 #include "net/http/http_log_util.h"
 #include "net/log/net_log_capture_mode.h"
+#include "net/spdy/platform/api/spdy_estimate_memory_usage.h"
 
 using base::StringPiece;
 using std::dec;
@@ -89,6 +90,11 @@ class SpdyHeaderBlock::Storage {
 
   size_t bytes_allocated() const { return arena_.status().bytes_allocated(); }
 
+  // TODO(xunjieli): https://crbug.com/669108. Merge this with bytes_allocated()
+  size_t EstimateMemoryUsage() const {
+    return arena_.status().bytes_allocated();
+  }
+
  private:
   UnsafeArena arena_;
 };
@@ -299,6 +305,12 @@ void SpdyHeaderBlock::AppendValueOrAddHeader(const StringPiece key,
   iter->second.Append(GetStorage()->Write(value));
 }
 
+size_t SpdyHeaderBlock::EstimateMemoryUsage() const {
+  // TODO(xunjieli): https://crbug.com/669108. Also include |block_| when EMU()
+  // supports linked_hash_map.
+  return SpdyEstimateMemoryUsage(storage_);
+}
+
 void SpdyHeaderBlock::AppendHeader(const StringPiece key,
                                    const StringPiece value) {
   auto storage = GetStorage();