Adds a new class HttpCache::Writers for multiple cache transactions reading from the network.

net/http/http_cache_transaction.h

Index: net/http/http_cache_transaction.h
diff --git a/net/http/http_cache_transaction.h b/net/http/http_cache_transaction.h
index 51c0db70256cbd31505ca20ffba6486ab4c36aad..3fac137d99ea292d9b8f9a6f9c274c6600c02a4f 100644
--- a/net/http/http_cache_transaction.h
+++ b/net/http/http_cache_transaction.h
@@ -167,6 +167,9 @@ class HttpCache::Transaction : public HttpTransaction {
   // Returns the estimate of dynamically allocated memory in bytes.
   size_t EstimateMemoryUsage() const;
 
+  RequestPriority priority() { return priority_; }

[jkarlin, 2017/06/12 18:30:32]

this should be a const function

[shivanisha, 2017/06/14 02:33:16]

done

+  PartialData* partial() { return partial_.get(); }
+
  private:
   static const size_t kNumValidationHeaders = 2;
   // Helper struct to pair a header name with its value, for