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 19 matching lines @@
             if (!f->isLocalFrame())
                 continue;
             frameLoadType = toLocalFrame(f)->loader().loadType();
             if (frameLoadType == FrameLoadTypeBackForward)
                 return WebCachePolicy::ReturnCacheDataElseLoad;
             if (frameLoadType == FrameLoadTypeReloadBypassingCache)
                 return WebCachePolicy::BypassingCache;
             if (frameLoadType == FrameLoadTypeReload)
                 return WebCachePolicy::ValidatingCacheData;
         }
+        // Returns UseProtocolCachePolicy for other cases, mainly
+        // FrameLoadTypeStandard and FrameLoadTypeReloadMainResource.

[hiroshige, 2016/07/28 03:38:45]

Is it referring to |frameLoadType| assigned at Line 256, not that assigned at
Line 245?
(For FrameLoadTypeReloadMainResource assigned at Line 245, ValidatingCacheData
is returned at Line 251, not at Line 267.)

[Takashi Toyoshima, 2016/07/29 13:24:49]

Ah, right.
This is confusing. Can I stop reusing the same variable for parent frame's load
type? That makes this comment understandable too.

+        // 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