Improve memory estimate of SpdySessionPool in net/ MemoryDumpProvider.

net/spdy/spdy_buffer_producer.h

Index: net/spdy/spdy_buffer_producer.h
diff --git a/net/spdy/spdy_buffer_producer.h b/net/spdy/spdy_buffer_producer.h
index 8d09f7b4ea29542751b63eb5ec9b23f9e35face9..5b18c1878aa4fb3b552e99e2f050e85341777e93 100644
--- a/net/spdy/spdy_buffer_producer.h
+++ b/net/spdy/spdy_buffer_producer.h
@@ -27,6 +27,9 @@ class NET_EXPORT_PRIVATE SpdyBufferProducer {
 
   virtual ~SpdyBufferProducer();
 
+  // Returns the estimate of dynamically allocated memory in bytes.
+  virtual size_t EstimateMemoryUsage() const = 0;
+
  private:
   DISALLOW_COPY_AND_ASSIGN(SpdyBufferProducer);
 };
@@ -40,6 +43,8 @@ class NET_EXPORT_PRIVATE SimpleBufferProducer : public SpdyBufferProducer {
 
   std::unique_ptr<SpdyBuffer> ProduceBuffer() override;
 
+  size_t EstimateMemoryUsage() const override;
+
  private:
   std::unique_ptr<SpdyBuffer> buffer_;