FrameFetchContext: add clear comments how FrameLoadTypeReloadMainResource works

third_party/WebKit/Source/core/loader/FrameFetchContext.cpp

 /*
  * Copyright (C) 2013 Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are
  * met:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
  *     * Redistributions in binary form must reproduce the above
@@ skipping 200 matching lines @@
         CachePolicy parentCachePolicy = toLocalFrame(parentFrame)->document()->fetcher()->context().getCachePolicy();
         if (parentCachePolicy != CachePolicyVerify)
             return parentCachePolicy;
     }
 
     if (loadType == FrameLoadTypeReload)
         return CachePolicyRevalidate;
 
     if (m_documentLoader && m_documentLoader->request().getCachePolicy() == WebCachePolicy::ReturnCacheDataElseLoad)
         return CachePolicyHistoryBuffer;
+
+    // Returns CachePolicyVerify for other cases, mainly FrameLoadTypeStandard
+    // and FrameLoadTypeReloadMainResource. See public/web/WebFrameLoadType.h
+    // to know how these load types work.
     return CachePolicyVerify;
 }
 
 static WebCachePolicy memoryCachePolicyToResourceRequestCachePolicy(const CachePolicy policy)
 {
     if (policy == CachePolicyVerify)
         return WebCachePolicy::UseProtocolCachePolicy;
     if (policy == CachePolicyRevalidate)
         return WebCachePolicy::ValidatingCacheData;
     if (policy == CachePolicyReload)
@@ skipping 11 matching lines @@
         if (request.httpMethod() == "POST" && frameLoadType == FrameLoadTypeBackForward)
             return WebCachePolicy::ReturnCacheDataDontLoad;
         if (!frame()->host()->overrideEncoding().isEmpty())
             return WebCachePolicy::ReturnCacheDataElseLoad;
         if (frameLoadType == FrameLoadTypeReloadMainResource || request.isConditional() || request.httpMethod() == "POST")
             return WebCachePolicy::ValidatingCacheData;
 
         for (Frame* f = frame(); f; f = f->tree().parent()) {
             if (!f->isLocalFrame())
                 continue;
-            frameLoadType = toLocalFrame(f)->loader().loadType();
-            if (frameLoadType == FrameLoadTypeBackForward)
+            FrameLoadType parentFrameLoadType = toLocalFrame(f)->loader().loadType();
+            if (parentFrameLoadType == FrameLoadTypeBackForward)
                 return WebCachePolicy::ReturnCacheDataElseLoad;
-            if (frameLoadType == FrameLoadTypeReloadBypassingCache)
+            if (parentFrameLoadType == FrameLoadTypeReloadBypassingCache)
                 return WebCachePolicy::BypassingCache;
-            if (frameLoadType == FrameLoadTypeReload)
+            if (parentFrameLoadType == FrameLoadTypeReload)
                 return WebCachePolicy::ValidatingCacheData;
         }
+        // Returns UseProtocolCachePolicy for other cases, parent frames not
+        // having special kinds of FrameLoadType as they are checked inside
+        // the for loop above, or |frameLoadType| being FrameLoadTypeStandard.
+        // See public/web/WebFrameLoadType.h to know how these load types work.
         return WebCachePolicy::UseProtocolCachePolicy;
     }
 
     // For users on slow connections, we want to avoid blocking the parser in
     // the main frame on script loads inserted via document.write, since it can
     // add significant delays before page content is displayed on the screen.
     if (type == Resource::Script && isMainFrame() && m_document && shouldDisallowFetchForMainFrameScript(request, defer, *m_document))
         return WebCachePolicy::ReturnCacheDataDontLoad;
 
     if (request.isConditional())
@@ skipping 542 matching lines @@
 }
 
 DEFINE_TRACE(FrameFetchContext)
 {
     visitor->trace(m_document);
     visitor->trace(m_documentLoader);
     FetchContext::trace(visitor);
 }
 
 } // namespace blink