Combine and make const RequiresValidation() and ConditionalizeRequest().

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..b0f20b3b49e380163d76f8424ca3ab84d0afd46b 100644
--- a/net/http/http_cache_transaction.h
+++ b/net/http/http_cache_transaction.h
@@ -244,6 +244,14 @@ class HttpCache::Transaction : public HttpTransaction {
     VALIDATION_CAUSE_MAX
   };
 
+  // What, if any, network confirmation for a cache entry is required.
+  enum EntryValidationStatus {
+    USABLE,                             // Can be used without server ok.
+    REQUIRES_VALIDATION,                // Need to check with server.
+    REQUIRES_VALIDATION_VARY_MISMATCH,  // Vary mismatch allows last-modified.
+    REQUIRES_REFETCH                    // Entry needs to be fetched.

[shivanisha, 2017/05/02 16:03:26]

nit: prefer enum class for type safety.

+  };
+
   // Runs the state transition loop. Resets and calls |callback_| on exit,
   // unless the return value is ERR_IO_PENDING.
   int DoLoop(int result);
@@ -338,12 +346,12 @@ class HttpCache::Transaction : public HttpTransaction {
   // Returns network error code.
   int RestartNetworkRequestWithAuth(const AuthCredentials& credentials);
 
-  // Called to determine if we need to validate the cache entry before using it.
-  bool RequiresValidation();
+  // Helper function for GetEntryValidationStatus(). |*vary_mismatch| will
+  // be set to false unless validation is required because of a vary mismatch.
+  bool RequiresValidation(bool* vary_mismatch) const;
 
-  // Called to make the request conditional (to ask the server if the cached
-  // copy is valid).  Returns true if able to make the request conditional.
-  bool ConditionalizeRequest();
+  // Return the type of network validation required by the entry.
+  EntryValidationStatus GetEntryValidationStatus() const;
 
   // Makes sure that a 206 response is expected.  Returns true on success.
   // On success, handling_206_ will be set to true if we are processing a
@@ -464,7 +472,6 @@ class HttpCache::Transaction : public HttpTransaction {
   bool handling_206_;  // We must deal with this 206 response.
   bool cache_pending_;  // We are waiting for the HttpCache.
   bool done_reading_;  // All available data was read.
-  bool vary_mismatch_;  // The request doesn't match the stored vary data.
   bool couldnt_conditionalize_request_;
   bool bypass_lock_for_test_;  // A test is exercising the cache lock.
   bool fail_conditionalization_for_test_;  // Fail ConditionalizeRequest.
@@ -476,19 +483,21 @@ class HttpCache::Transaction : public HttpTransaction {
   std::unique_ptr<PartialData> partial_;  // We are dealing with range requests.
   CompletionCallback io_callback_;
 
-  // Members used to track data for histograms.
+  // Members used to track data for histograms.  The state of these fields
+  // do not affect the behavior of the transaction, and hence can be changed
+  // in const methods.
   // This cache_entry_status_ takes precedence over
   // response_.cache_entry_status. In fact, response_.cache_entry_status must be
   // kept in sync with cache_entry_status_ (via SetResponse and
   // UpdateCacheEntryStatus).
   HttpResponseInfo::CacheEntryStatus cache_entry_status_;
-  ValidationCause validation_cause_;
+  mutable ValidationCause validation_cause_;
   base::TimeTicks entry_lock_waiting_since_;
   base::TimeTicks first_cache_access_since_;
   base::TimeTicks send_request_since_;
   base::Time open_entry_last_used_;
-  base::TimeDelta stale_entry_freshness_;
-  base::TimeDelta stale_entry_age_;
+  mutable base::TimeDelta stale_entry_freshness_;
+  mutable base::TimeDelta stale_entry_age_;
 
   int64_t total_received_bytes_;
   int64_t total_sent_bytes_;