Don't use a low-quality filter when painting images while others are animating.

third_party/WebKit/Source/core/layout/ImageQualityController.cpp

Index: third_party/WebKit/Source/core/layout/ImageQualityController.cpp
diff --git a/third_party/WebKit/Source/core/layout/ImageQualityController.cpp b/third_party/WebKit/Source/core/layout/ImageQualityController.cpp
index d5e6622e97b610a78a9c76032ba19e01f17cfab9..517cd8e72af135007df6d2637effa82226c405bc 100644
--- a/third_party/WebKit/Source/core/layout/ImageQualityController.cpp
+++ b/third_party/WebKit/Source/core/layout/ImageQualityController.cpp
@@ -89,7 +89,6 @@ ImageQualityController::~ImageQualityController()
 
 ImageQualityController::ImageQualityController()
     : m_timer(adoptPtr(new Timer<ImageQualityController>(this, &ImageQualityController::highQualityRepaintTimerFired)))
-    , m_animatedResizeIsActive(false)
     , m_liveResizeOptimizationIsActive(false)
 {
 }
@@ -108,14 +107,16 @@ void ImageQualityController::removeLayer(const LayoutObject& object, LayerSizeMa
     }
 }
 
-void ImageQualityController::set(const LayoutObject& object, LayerSizeMap* innerMap, const void* layer, const LayoutSize& size)
+void ImageQualityController::set(const LayoutObject& object, LayerSizeMap* innerMap, const void* layer, const LayoutSize& size, bool isResizing)
 {
     if (innerMap) {
         innerMap->set(layer, size);
+        m_objectLayerSizeMap.find(&object)->value.isResizing = isResizing;
     } else {
-        LayerSizeMap newInnerMap;
-        newInnerMap.set(layer, size);
-        m_objectLayerSizeMap.set(&object, newInnerMap);
+        ObjectResizeInfo newResizeInfo;
+        newResizeInfo.layerSizeMap.set(layer, size);
+        newResizeInfo.isResizing = isResizing;
+        m_objectLayerSizeMap.set(&object, newResizeInfo);
     }
 }
 
@@ -123,17 +124,12 @@ void ImageQualityController::objectDestroyed(const LayoutObject& object)
 {
     m_objectLayerSizeMap.remove(&object);
     if (m_objectLayerSizeMap.isEmpty()) {
-        m_animatedResizeIsActive = false;
         m_timer->stop();
     }
 }
 
 void ImageQualityController::highQualityRepaintTimerFired(Timer<ImageQualityController>*)
 {
-    if (!m_animatedResizeIsActive && !m_liveResizeOptimizationIsActive)
-        return;
-    m_animatedResizeIsActive = false;
-
     for (auto* layoutObject : m_objectLayerSizeMap.keys()) {
         if (LocalFrame* frame = layoutObject->document().frame()) {
             // If this layoutObject's containing FrameView is in live resize, punt the timer and hold back for now.
@@ -142,8 +138,15 @@ void ImageQualityController::highQualityRepaintTimerFired(Timer<ImageQualityCont
                 return;
             }
         }
-        // TODO(wangxianzhu): Use LayoutObject::mutableForPainting().
-        const_cast<LayoutObject*>(layoutObject)->setShouldDoFullPaintInvalidation();
+        ObjectLayerSizeMap::iterator i = m_objectLayerSizeMap.find(layoutObject);
+        if (i != m_objectLayerSizeMap.end()) {
+            // Only invalidate the object if it is animating.
+            if (i->value.isResizing) {
+                // TODO(wangxianzhu): Use LayoutObject::mutableForPainting().
+                const_cast<LayoutObject*>(layoutObject)->setShouldDoFullPaintInvalidation();
+            }
+            i->value.isResizing = false;
+        }
     }
 
     m_liveResizeOptimizationIsActive = false;
@@ -169,7 +172,12 @@ bool ImageQualityController::shouldPaintAtLowQuality(const LayoutObject& object,
 
     // Look ourselves up in the hashtables.
     ObjectLayerSizeMap::iterator i = m_objectLayerSizeMap.find(&object);
-    LayerSizeMap* innerMap = i != m_objectLayerSizeMap.end() ? &i->value : 0;
+    LayerSizeMap* innerMap = nullptr;
+    bool objectIsResizing = false;
+    if (i != m_objectLayerSizeMap.end()) {
+        innerMap = &i->value.layerSizeMap;
+        objectIsResizing = i->value.isResizing;
+    }
     LayoutSize oldSize;
     bool isFirstResize = true;
     if (innerMap) {
@@ -184,7 +192,7 @@ bool ImageQualityController::shouldPaintAtLowQuality(const LayoutObject& object,
     if (LocalFrame* frame = object.document().frame()) {
         bool frameViewIsCurrentlyInLiveResize = frame->view() && frame->view()->inLiveResize();
         if (frameViewIsCurrentlyInLiveResize) {
-            set(object, innerMap, layer, layoutSize);
+            set(object, innerMap, layer, layoutSize, true);

[pdr., 2016/02/10 19:06:30]

Should this be objectIsResizing instead of true?

[chrishtr, 2016/02/10 19:16:32]

No, because otherwise the callback in
ImageQualityController::highQualityRepaintTimerFired won't necessarily
invalidate
the object at the end of the frame resize.

             restartTimer();
             m_liveResizeOptimizationIsActive = true;
             return true;
@@ -202,10 +210,11 @@ bool ImageQualityController::shouldPaintAtLowQuality(const LayoutObject& object,
         return false;
     }
 
-    // If an animated resize is active, paint in low quality and kick the timer ahead.
-    if (m_animatedResizeIsActive) {
-        set(object, innerMap, layer, layoutSize);
-        if (oldSize != layoutSize)
+    // If an animated resize is active for this object, paint in low quality and kick the timer ahead.
+    if (objectIsResizing) {
+        bool sizesChanged = oldSize != layoutSize;
+        set(object, innerMap, layer, layoutSize, sizesChanged);
+        if (sizesChanged)
             restartTimer();
         return true;
     }
@@ -214,7 +223,7 @@ bool ImageQualityController::shouldPaintAtLowQuality(const LayoutObject& object,
     // size and set the timer.
     if (isFirstResize || oldSize == layoutSize) {
         restartTimer();
-        set(object, innerMap, layer, layoutSize);
+        set(object, innerMap, layer, layoutSize, false);
         return false;
     }
     // If the timer is no longer active, draw at high quality and don't
@@ -223,12 +232,10 @@ bool ImageQualityController::shouldPaintAtLowQuality(const LayoutObject& object,
         removeLayer(object, innerMap, layer);
         return false;
     }
-
     // This object has been resized to two different sizes while the timer
     // is active, so draw at low quality, set the flag for animated resizes and
     // the object to the list for high quality redraw.
-    set(object, innerMap, layer, layoutSize);
-    m_animatedResizeIsActive = true;
+    set(object, innerMap, layer, layoutSize, true);
     restartTimer();
     return true;
 }