Tweak priorities of paint invalidation reasons

third_party/WebKit/Source/core/paint/ObjectPaintInvalidator.cpp

Index: third_party/WebKit/Source/core/paint/ObjectPaintInvalidator.cpp
diff --git a/third_party/WebKit/Source/core/paint/ObjectPaintInvalidator.cpp b/third_party/WebKit/Source/core/paint/ObjectPaintInvalidator.cpp
index 9b3e8de3fda26c2bb1947877dc405341a5772b82..a60990f0d0c0e3428339cfcbc39db469013f5106 100644
--- a/third_party/WebKit/Source/core/paint/ObjectPaintInvalidator.cpp
+++ b/third_party/WebKit/Source/core/paint/ObjectPaintInvalidator.cpp
@@ -86,10 +86,13 @@ PaintInvalidationReason ObjectPaintInvalidator::computePaintInvalidationReason()
     if (m_object.shouldDoFullPaintInvalidation())
         return m_object.fullPaintInvalidationReason();
 
+    if (m_context.oldBounds.isEmpty() && m_context.newBounds.isEmpty())
+        return PaintInvalidationNone;
+
     if (backgroundObscurationChanged)
         return PaintInvalidationBackgroundObscurationChange;
 
-    if (m_object.paintedOutputOfObjectHasNoEffect())
+    if (m_object.paintedOutputOfObjectHasNoEffectRegardlessOfSize())
         return PaintInvalidationNone;
 
     const ComputedStyle& style = m_object.styleRef();
@@ -106,12 +109,7 @@ PaintInvalidationReason ObjectPaintInvalidator::computePaintInvalidationReason()
     // If the bounds are the same then we know that none of the statements below
     // can match, so we can early out.
     if (m_context.oldBounds == m_context.newBounds)
-        return locationChanged && !m_context.oldBounds.isEmpty() ? PaintInvalidationLocationChange : PaintInvalidationNone;
-
-    // If we shifted, we don't know the exact reason so we are conservative and trigger a full invalidation. Shifting could
-    // be caused by some layout property (left / top) or some in-flow layoutObject inserted / removed before us in the tree.
-    if (m_context.newBounds.location() != m_context.oldBounds.location())
-        return PaintInvalidationBoundsChange;
+        return locationChanged ? PaintInvalidationLocationChange : PaintInvalidationProbablyNone;
 
     // If the size is zero on one of our bounds then we know we're going to have
     // to do a full invalidation of either old bounds or new bounds.
@@ -120,6 +118,11 @@ PaintInvalidationReason ObjectPaintInvalidator::computePaintInvalidationReason()
     if (m_context.newBounds.isEmpty())
         return PaintInvalidationBecameInvisible;
 
+    // If we shifted, we don't know the exact reason so we are conservative and trigger a full invalidation. Shifting could
+    // be caused by some layout property (left / top) or some in-flow layoutObject inserted / removed before us in the tree.
+    if (m_context.newBounds.location() != m_context.oldBounds.location())
+        return PaintInvalidationBoundsChange;
+
     if (locationChanged)
         return PaintInvalidationLocationChange;
 
@@ -131,7 +134,7 @@ void ObjectPaintInvalidator::invalidateSelectionIfNeeded(PaintInvalidationReason
     // Update selection rect when we are doing full invalidation (in case that the object is moved,
     // composite status changed, etc.) or shouldInvalidationSelection is set (in case that the
     // selection itself changed).
-    bool fullInvalidation = isFullPaintInvalidationReason(reason);
+    bool fullInvalidation = isImmediateFullPaintInvalidationReason(reason);
     if (!fullInvalidation && !m_object.shouldInvalidateSelection())
         return;
 
@@ -159,6 +162,7 @@ PaintInvalidationReason ObjectPaintInvalidator::invalidatePaintIfNeededWithCompu
 
     switch (reason) {
     case PaintInvalidationNone:
+    case PaintInvalidationProbablyNone:
         // TODO(trchen): Currently we don't keep track of paint offset of layout objects.
         // There are corner cases that the display items need to be invalidated for paint offset
         // mutation, but incurs no pixel difference (i.e. bounds stay the same) so no rect-based
@@ -175,7 +179,7 @@ PaintInvalidationReason ObjectPaintInvalidator::invalidatePaintIfNeededWithCompu
     case PaintInvalidationDelayedFull:
         return PaintInvalidationDelayedFull;
     default:
-        DCHECK(isFullPaintInvalidationReason(reason));
+        DCHECK(isImmediateFullPaintInvalidationReason(reason));
         fullyInvalidatePaint(reason, m_context.oldBounds, m_context.newBounds);
     }