HttpCache::Transaction layer allowing parallel validation

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 a8fca54228e8d8f6cadda6b947e90ab7bf24cd94..7ecf7cdd8e4d804276d72cd544c8e9aad0b5b5c2 100644
--- a/net/http/http_cache_transaction.h
+++ b/net/http/http_cache_transaction.h
@@ -164,6 +164,10 @@ class HttpCache::Transaction : public HttpTransaction {
   int ResumeNetworkStart() override;
   void GetConnectionAttempts(ConnectionAttempts* out) const override;
 
+  // Invoked when parallel validation cannot proceed due to response failure
+  // and this transaction needs to be restarted.
+  void SetValidatingCannotProceed();
+
   // Returns the estimate of dynamically allocated memory in bytes.
   size_t EstimateMemoryUsage() const;
 
@@ -220,6 +224,9 @@ class HttpCache::Transaction : public HttpTransaction {
     STATE_PARTIAL_HEADERS_RECEIVED,
     STATE_CACHE_READ_METADATA,
     STATE_CACHE_READ_METADATA_COMPLETE,
+    STATE_HEADERS_PHASE_CANNOT_PROCEED,
+    STATE_FINISH_HEADERS,
+    STATE_FINISH_HEADERS_COMPLETE,
 
     // These states are entered from Read/AddTruncatedFlag.
     STATE_NETWORK_READ,
@@ -286,6 +293,9 @@ class HttpCache::Transaction : public HttpTransaction {
   int DoTruncateCachedMetadata();
   int DoTruncateCachedMetadataComplete(int result);
   int DoPartialHeadersReceived();
+  int DoHeadersPhaseCannotProceed();
+  int DoFinishHeaders(int result);
+  int DoFinishHeadersComplete(int result);
   int DoCacheReadMetadata();
   int DoCacheReadMetadataComplete(int result);
   int DoNetworkRead();
@@ -457,6 +467,7 @@ class HttpCache::Transaction : public HttpTransaction {
   const HttpResponseInfo* new_response_;
   std::string cache_key_;
   Mode mode_;
+  Mode original_mode_;  // Used when restarting the transaction.
   bool reading_;  // We are already reading. Never reverts to false once set.
   bool invalid_range_;  // We may bypass the cache for this request.
   bool truncated_;  // We don't have all the response data.