Exposing CacheEntryStatus (former TransactionPattern) via UrlRequest

net/http/http_response_info.h

Index: net/http/http_response_info.h
diff --git a/net/http/http_response_info.h b/net/http/http_response_info.h
index a67e4ecd3f16f6b2c1b4dfb4e479070f40596fec..046774250f62b310cab2e7f9b34386b7812b186a 100644
--- a/net/http/http_response_info.h
+++ b/net/http/http_response_info.h
@@ -46,6 +46,34 @@ class NET_EXPORT HttpResponseInfo {
     NUM_OF_CONNECTION_INFOS,
   };
 
+  // Used for categorizing transactions for reporting in histograms.
+  // CacheEntryStatus covers relatively common use cases being measured and
+  // considered for optimization. Many use cases that are more complex or
+  // uncommon are binned as OTHER, and details are not reported.
+  // NOTE: This enumeration is used in histograms, so please do not add entries
+  // in the middle.
+  enum CacheEntryStatus {
+    ENTRY_UNDEFINED,
+    // Complex or uncommon case. E.g., auth (401), partial responses (206), ...
+    ENTRY_OTHER,
+    // The response was not in the cache. Implies !was_cached &&
+    // network_accessed.
+    ENTRY_NOT_IN_CACHE,
+    // The response was served from the cache and no validation was needed.
+    // Implies was_cached && !network_accessed.
+    ENTRY_USED,
+    // The response was validated and served from the cache. Implies was_cached
+    // && network_accessed.
+    ENTRY_VALIDATED,
+    // There was a stale entry in the cache that was updated. Implies
+    // !was_cached && network_accessed.
+    ENTRY_UPDATED,
+    // The HTTP request didn't allow a conditional request. Implies !was_cached
+    // && network_accessed.
+    ENTRY_CANT_CONDITIONALIZE,
+    ENTRY_MAX,
+  };
+
   HttpResponseInfo();
   HttpResponseInfo(const HttpResponseInfo& rhs);
   ~HttpResponseInfo();
@@ -77,6 +105,9 @@ class NET_EXPORT HttpResponseInfo {
   // value even if the request fails.
   bool was_cached;
 
+  // How this response was handled by the HTTP cache.
+  CacheEntryStatus cache_entry_status;
+
   // True if the request was fetched from cache rather than the network
   // because of a LOAD_FROM_CACHE_IF_OFFLINE flag when the system
   // was unable to contact the server.