Reload image bypassing the cache

Source/core/loader/ImageLoader.cpp

Index: Source/core/loader/ImageLoader.cpp
diff --git a/Source/core/loader/ImageLoader.cpp b/Source/core/loader/ImageLoader.cpp
index ecb7d10eda0468355d192b96f704e1363bb43391..73b07364414860bd2e0e53cef7a4092cd1e3921c 100644
--- a/Source/core/loader/ImageLoader.cpp
+++ b/Source/core/loader/ImageLoader.cpp
@@ -100,7 +100,7 @@ public:
             if (Heap::willObjectBeLazilySwept(m_loader))
                 return;
 #endif
-            m_loader->doUpdateFromElement(m_shouldBypassMainWorldCSP, m_updateBehavior);
+            m_loader->doUpdateFromElement(m_shouldBypassMainWorldCSP, m_updateBehavior, false);

[Yoav Weiss, 2015/04/29 06:13:24]

This shouldn't be a boolean, but an enum. That way we can tell what it does from
when calling the method.

Also - is the bypassCache state always false for images that are asynchronously
loaded? Can you explain the logic?

         }
     }
 
@@ -237,7 +237,7 @@ inline void ImageLoader::enqueueImageLoadingMicroTask(UpdateFromElementBehavior
     m_loadDelayCounter = IncrementLoadEventDelayCount::create(m_element->document());
 }
 
-void ImageLoader::doUpdateFromElement(BypassMainWorldBehavior bypassBehavior, UpdateFromElementBehavior updateBehavior)
+void ImageLoader::doUpdateFromElement(BypassMainWorldBehavior bypassBehavior, UpdateFromElementBehavior updateBehavior, bool bypassCache)
 {
     // FIXME: According to
     // http://www.whatwg.org/specs/web-apps/current-work/multipage/embedded-content.html#the-img-element:the-img-element-55
@@ -265,6 +265,8 @@ void ImageLoader::doUpdateFromElement(BypassMainWorldBehavior bypassBehavior, Up
         ResourceLoaderOptions resourceLoaderOptions = ResourceFetcher::defaultResourceOptions();
         ResourceRequest resourceRequest(url);
         resourceRequest.setFetchCredentialsMode(WebURLRequest::FetchCredentialsModeSameOrigin);
+        if (bypassCache)
+            resourceRequest.setCachePolicy(ResourceRequestCachePolicy::ReloadBypassingCache);

[Nate Chapin, 2015/04/30 20:59:41]

I'm not thrilled with the need to bypass the cache when loading the real image
contents. That seems like it could break if LoFi images are enabled, then
disabled. Perhaps LoFi images could include Cache-Control: headers?

[megjablon, 2015/04/30 22:00:54]

We discussed using no-store, but want LoFi images to be cached since the goal of
Data Saver is to be conservative with users' data. We want to bypass the cache
and load the original image only when the user explicitly asks to.

[Nate Chapin, 2015/04/30 22:26:54]

LoFi images would be replaced with the real image one-at-a-time, right?
ResourceFetcher already has a setting to auto load images, I wonder if we could
modify that to handle this use case.

[megjablon, 2015/04/30 22:35:50]

Yes, we want to only replace one real image at a time. What does auto loading an
image do?

         if (isHTMLPictureElement(element()->parentNode()) || !element()->fastGetAttribute(HTMLNames::srcsetAttr).isNull())
             resourceRequest.setRequestContext(WebURLRequest::RequestContextImageSet);
         FetchRequest request(resourceRequest, element()->localName(), resourceLoaderOptions);
@@ -340,7 +342,7 @@ void ImageLoader::doUpdateFromElement(BypassMainWorldBehavior bypassBehavior, Up
     updatedHasPendingEvent();
 }
 
-void ImageLoader::updateFromElement(UpdateFromElementBehavior updateBehavior)
+void ImageLoader::updateFromElement(UpdateFromElementBehavior updateBehavior, bool bypassCache)
 {
     AtomicString imageSourceURL = m_element->imageSourceURL();
     m_suppressErrorEvents = (updateBehavior == UpdateSizeChanged);
@@ -360,7 +362,7 @@ void ImageLoader::updateFromElement(UpdateFromElementBehavior updateBehavior)
 
     KURL url = imageSourceToKURL(imageSourceURL);
     if (shouldLoadImmediately(url)) {
-        doUpdateFromElement(DoNotBypassMainWorldCSP, updateBehavior);
+        doUpdateFromElement(DoNotBypassMainWorldCSP, updateBehavior, bypassCache);
         return;
     }
     // Allow the idiom "img.src=''; img.src='.." to clear down the image before