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 2dce1a1de07c9577c835cfcb8b2f2ca7bbf3e5c9..eb90012fe5053b8642b88487334e924ac18df8e5 100644
--- a/net/http/http_response_info.h
+++ b/net/http/http_response_info.h
@@ -44,6 +44,34 @@ 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 {
+    UNDEFINED,

[jkarlin, 2016/07/06 17:09:41]

Please prefix the names with ENTRY_

e.g., ENTRY_UNDEFINED, ENTRY_OTHER, ENTRY_NOT_IN_CACHE, ENTRY_USED,
ENTRY_VALIDATED, ENTRY_UPDATED, ENTRY_CANT_CONDITIONALIZE, ENTRY_MAX

[jamartin, 2016/07/07 21:36:38]

Done.

Why? if I may ask. I considered the ENTRY_ prefix very much redundant given the
CacheEntryStatus:: qualification.

+    // Complex or uncommon case (e.g., partial responses - 206).
+    OTHER,
+    // The response was not in the cache. Implies !was_cached &&
+    // network_accessed.
+    NOT_IN_CACHE,
+    // The response was served from the cache and no validation was needed.
+    // Implies was_cached && !network_accessed.
+    USED,
+    // The response was validated and served from the cache. Implies was_cached
+    // && network_accessed.
+    VALIDATED,
+    // There was a stale entry in the cache that was updated. Implies
+    // !was_cached && network_accessed.
+    UPDATED,
+    // The HTTP request didn't allow a conditional request. Implies !was_cached
+    // && network_accessed.
+    CANT_CONDITIONALIZE,
+    MAX,
+  };
+
   HttpResponseInfo();
   HttpResponseInfo(const HttpResponseInfo& rhs);
   ~HttpResponseInfo();
@@ -75,6 +103,9 @@ 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.