Add GetExpirationTimes() to HttpResponseHeader.

net/http/http_response_headers.h

Index: net/http/http_response_headers.h
diff --git a/net/http/http_response_headers.h b/net/http/http_response_headers.h
index 653eacc4d44e30b86d15c41532ec2514ef8ba435..43639916d1fb0e5f4c816cae8181c966a313e97f 100644
--- a/net/http/http_response_headers.h
+++ b/net/http/http_response_headers.h
@@ -30,12 +30,6 @@ namespace net {
 
 class HttpByteRange;
 
-enum ValidationType {
-  VALIDATION_NONE,          // The resource is fresh.
-  VALIDATION_ASYNCHRONOUS,  // The resource requires async revalidation.
-  VALIDATION_SYNCHRONOUS    // The resource requires sync revalidation.
-};
-
 // HttpResponseHeaders: parses and holds HTTP response headers.
 class NET_EXPORT HttpResponseHeaders
     : public base::RefCountedThreadSafe<HttpResponseHeaders> {
@@ -51,12 +45,26 @@ class NET_EXPORT HttpResponseHeaders
   static const PersistOptions PERSIST_SANS_RANGES = 1 << 4;
   static const PersistOptions PERSIST_SANS_SECURITY_STATE = 1 << 5;
 
-  struct FreshnessLifetimes {
+  struct ExpirationTimes {
+    base::Time GetFreshnessExpiry() const {
+      return corrected_response_time + freshness_lifetime;
+    }
+
+    base::Time GetStalenessExpiry() const {
+      return corrected_response_time + staleness_lifetime;
+    }
+
+    // The |base::Time::Now()| value for which this request would have an age of
+    // exactly zero. You can subtract this from |base::Time::Now()| to get the
+    // current age.
+    base::Time corrected_response_time;
+
     // How long the resource will be fresh for.
-    base::TimeDelta freshness;
+    base::TimeDelta freshness_lifetime;
+
     // How long after becoming not fresh that the resource will be stale but
     // usable (if async revalidation is enabled).
-    base::TimeDelta staleness;
+    base::TimeDelta staleness_lifetime;
   };
 
   static const char kContentRange[];
@@ -225,17 +233,12 @@ class NET_EXPORT HttpResponseHeaders
   // redirect.
   static bool IsRedirectResponseCode(int response_code);
 
-  // Returns VALIDATION_NONE if the response can be reused without
-  // validation. VALIDATION_ASYNCHRONOUS means the response can be re-used, but
-  // asynchronous revalidation must be performed. VALIDATION_SYNCHRONOUS means
-  // that the result cannot be reused without revalidation.
-  // The result is relative to the current_time parameter, which is
-  // a parameter to support unit testing.  The request_time parameter indicates
-  // the time at which the request was made that resulted in this response,
-  // which was received at response_time.
-  ValidationType RequiresValidation(const base::Time& request_time,
-                                    const base::Time& response_time,
-                                    const base::Time& current_time) const;
+  // Returns an ExpirationTimes struct which can be used to calculate the
+  // freshness and stale-white-revalidate status of this response. The values in
+  // the ExpirationTimes struct do not depend on the current time, so they can
+  // be stored and used later as well.
+  ExpirationTimes GetExpirationTimes(const base::Time& request_time,
+                                     const base::Time& response_time) const;
 
   // Calculates the amount of time the server claims the response is fresh from
   // the time the response was generated.  See section 13.2.4 of RFC 2616.  See
@@ -243,14 +246,9 @@ class NET_EXPORT HttpResponseHeaders
   // the definition of FreshnessLifetimes above for the meaning of the return
   // value.  See RFC 5861 section 3 for the definition of
   // stale-while-revalidate.
-  FreshnessLifetimes GetFreshnessLifetimes(
-      const base::Time& response_time) const;
-
-  // Returns the age of the response.  See section 13.2.3 of RFC 2616.
-  // See RequiresValidation for a description of this method's parameters.
-  base::TimeDelta GetCurrentAge(const base::Time& request_time,
-                                const base::Time& response_time,
-                                const base::Time& current_time) const;
+  void CalculateLifetimes(const base::Time& response_time,
+                          base::TimeDelta* out_freshness_lifetime,
+                          base::TimeDelta* out_staleness_lifetime) const;
 
   // The following methods extract values from the response headers.  If a
   // value is not present, or is invalid, then false is returned.  Otherwise,