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

Source/platform/network/ResourceRequest.cpp

Index: Source/platform/network/ResourceRequest.cpp
diff --git a/Source/platform/network/ResourceRequest.cpp b/Source/platform/network/ResourceRequest.cpp
index b3d16b8b4bf1185f3f46e15fa50080c3bf4cf033..2c46ef15cf671772fccf1162e4eb35ce9d132d3d 100644
--- a/Source/platform/network/ResourceRequest.cpp
+++ b/Source/platform/network/ResourceRequest.cpp
@@ -314,8 +314,41 @@ bool ResourceRequest::isConditional() const
         || m_httpHeaderFields.contains("If-Modified-Since")
         || m_httpHeaderFields.contains("If-None-Match")
         || m_httpHeaderFields.contains("If-Range")
-        || m_httpHeaderFields.contains("If-Unmodified-Since")
-        || m_httpHeaderFields.contains("Cache-Control"));
+        || m_httpHeaderFields.contains("If-Unmodified-Since"));
+}
+
+
+static const AtomicString& cacheControlHeaderString()
+{
+    DEFINE_STATIC_LOCAL(const AtomicString, cacheControlHeader, ("cache-control", AtomicString::ConstructFromLiteral));
+    return cacheControlHeader;
+}
+
+static const AtomicString& pragmaHeaderString()
+{
+    DEFINE_STATIC_LOCAL(const AtomicString, pragmaHeader, ("pragma", AtomicString::ConstructFromLiteral));
+    return pragmaHeader;
+}
+
+bool ResourceRequest::cacheControlContainsNoCache()
+{
+    if (!m_cacheControlHeader.parsed)
+        m_cacheControlHeader = parseCacheControlDirectives(m_httpHeaderFields.get(cacheControlHeaderString()), m_httpHeaderFields.get(pragmaHeaderString()));
+    return m_cacheControlHeader.containsNoCache;
+}
+
+bool ResourceRequest::cacheControlContainsNoStore()
+{
+    if (!m_cacheControlHeader.parsed)
+        m_cacheControlHeader = parseCacheControlDirectives(m_httpHeaderFields.get(cacheControlHeaderString()), m_httpHeaderFields.get(pragmaHeaderString()));
+    return m_cacheControlHeader.containsNoStore;
+}
+
+bool ResourceRequest::hasCacheValidatorFields()
+{
+    DEFINE_STATIC_LOCAL(const AtomicString, lastModifiedHeader, ("last-modified", AtomicString::ConstructFromLiteral));
+    DEFINE_STATIC_LOCAL(const AtomicString, eTagHeader, ("etag", AtomicString::ConstructFromLiteral));
+    return !m_httpHeaderFields.get(lastModifiedHeader).isEmpty() || !m_httpHeaderFields.get(eTagHeader).isEmpty();
 }
 
 double ResourceRequest::defaultTimeoutInterval()