Do not show image placeholders for CSS sprites

third_party/WebKit/Source/core/css/resolver/ElementStyleResources.cpp

Index: third_party/WebKit/Source/core/css/resolver/ElementStyleResources.cpp
diff --git a/third_party/WebKit/Source/core/css/resolver/ElementStyleResources.cpp b/third_party/WebKit/Source/core/css/resolver/ElementStyleResources.cpp
index 5ef3af8e8908e949fc1952cb65be7d28d0b07271..b8cb1b322bd3704536570afd1241606cca5df8ee 100644
--- a/third_party/WebKit/Source/core/css/resolver/ElementStyleResources.cpp
+++ b/third_party/WebKit/Source/core/css/resolver/ElementStyleResources.cpp
@@ -28,6 +28,8 @@
 #include "core/css/CSSImageValue.h"
 #include "core/css/CSSURIValue.h"
 #include "core/dom/Document.h"
+#include "core/frame/Settings.h"
+#include "core/loader/resource/ImageResource.h"
 #include "core/style/ComputedStyle.h"
 #include "core/style/ContentData.h"
 #include "core/style/CursorData.h"
@@ -40,6 +42,8 @@
 #include "core/style/StyleInvalidImage.h"
 #include "core/style/StylePendingImage.h"
 #include "core/svg/SVGElementProxy.h"
+#include "platform/Length.h"
+#include "platform/LengthPoint.h"
 #include "platform/loader/fetch/ResourceFetcher.h"
 
 namespace blink {
@@ -114,12 +118,31 @@ void ElementStyleResources::loadPendingSVGDocuments(
   }
 }
 
+static bool isSprite(const ComputedStyle& style) {
+  // Simple hueristic to guess if CSS background image is used to create CSS

[Raj, 2017/04/04 08:02:02]

This heuristic is similar to:

https://cs.chromium.org/chromium/src/third_party/WebKit/Source/core/frame/Sma...

+  // sprites. For a legit background image it's very likely the height or the
+  // width will be set to auto. For CSS sprite image, height or width will
+  // probably be specified.
+
+  return style.hasBackgroundImage() &&
+         (!style.logicalHeight().isAuto() || !style.logicalWidth().isAuto());
+}
+
+static bool isImagePlaceholderAllowed(const Document& document,
+                                      const ComputedStyle& style) {
+  return document.settings() &&
+         document.settings()->getFetchImagePlaceholders() && !isSprite(style);
+}
+
 StyleImage* ElementStyleResources::loadPendingImage(
     ComputedStyle* style,
     StylePendingImage* pendingImage,
     CrossOriginAttributeValue crossOrigin) {
-  if (CSSImageValue* imageValue = pendingImage->cssImageValue())
-    return imageValue->cacheImage(*m_document, crossOrigin);
+  if (CSSImageValue* imageValue = pendingImage->cssImageValue()) {
+    return imageValue->cacheImage(
+        *m_document, crossOrigin,
+        isImagePlaceholderAllowed(*m_document, *style));
+  }
 
   if (CSSPaintValue* paintValue = pendingImage->cssPaintValue()) {
     StyleGeneratedImage* image = StyleGeneratedImage::create(*paintValue);
@@ -133,9 +156,11 @@ StyleImage* ElementStyleResources::loadPendingImage(
     return StyleGeneratedImage::create(*imageGeneratorValue);
   }
 
-  if (CSSImageSetValue* imageSetValue = pendingImage->cssImageSetValue())
-    return imageSetValue->cacheImage(*m_document, m_deviceScaleFactor,
-                                     crossOrigin);
+  if (CSSImageSetValue* imageSetValue = pendingImage->cssImageSetValue()) {
+    return imageSetValue->cacheImage(
+        *m_document, m_deviceScaleFactor, crossOrigin,
+        isImagePlaceholderAllowed(*m_document, *style));
+  }
 
   ASSERT_NOT_REACHED();
   return nullptr;