Reland "Allow cache reuse of some requests with Cache-Control headers"

Source/platform/network/HTTPParsers.h

Index: Source/platform/network/HTTPParsers.h
diff --git a/Source/platform/network/HTTPParsers.h b/Source/platform/network/HTTPParsers.h
index e6095e28c7509c751dd909c32b18205dc1654d3a..7bd7ed387ba58ae3d3a953c57640b76659d1a8d2 100644
--- a/Source/platform/network/HTTPParsers.h
+++ b/Source/platform/network/HTTPParsers.h
@@ -70,6 +70,23 @@ enum ReflectedXSSDisposition {
     BlockReflectedXSS
 };
 
+struct CacheControlHeader {
+    bool parsed : 1;
+    bool containsNoCache : 1;
+    bool containsNoStore : 1;
+    bool containsMustRevalidate : 1;
+    double maxAge;
+
+    CacheControlHeader()
+        : parsed(false)
+        , containsNoCache(false)
+        , containsNoStore(false)
+        , containsMustRevalidate(false)
+        , maxAge(0.0)
+    {
+    }
+};
+
 PLATFORM_EXPORT ContentDispositionType contentDispositionType(const String&);
 PLATFORM_EXPORT bool isValidHTTPHeaderValue(const String&);
 PLATFORM_EXPORT bool isValidHTTPToken(const String&);
@@ -82,6 +99,7 @@ PLATFORM_EXPORT void findCharsetInMediaType(const String& mediaType, unsigned& c
 PLATFORM_EXPORT ReflectedXSSDisposition parseXSSProtectionHeader(const String& header, String& failureReason, unsigned& failurePosition, String& reportURL);
 PLATFORM_EXPORT String extractReasonPhraseFromHTTPStatusLine(const String&);
 PLATFORM_EXPORT XFrameOptionsDisposition parseXFrameOptionsHeader(const String&);
+PLATFORM_EXPORT CacheControlHeader parseCacheControlDirectives(const AtomicString& cacheControlHeader, const AtomicString& pragmaHeader);
 
 // -1 could be set to one of the return parameters to indicate the value is not specified.
 PLATFORM_EXPORT bool parseRange(const String&, long long& rangeOffset, long long& rangeEnd, long long& rangeSuffixLength);