Implement SkImageFilter support in the compositor.

cc/damage_tracker.cc

Index: cc/damage_tracker.cc
diff --git a/cc/damage_tracker.cc b/cc/damage_tracker.cc
index b907e3e5edeec06dd112ac237b0809e6f5052e62..9dbd72fcfc0950a0f549c86eff56d80fc83122c2 100644
--- a/cc/damage_tracker.cc
+++ b/cc/damage_tracker.cc
@@ -51,7 +51,7 @@ static inline void expandDamageRectInsideRectWithFilters(FloatRect& damageRect,
     damageRect.unite(expandedDamageRect);
 }
 
-void CCDamageTracker::updateDamageTrackingState(const std::vector<CCLayerImpl*>& layerList, int targetSurfaceLayerID, bool targetSurfacePropertyChangedOnlyFromDescendant, const IntRect& targetSurfaceContentRect, CCLayerImpl* targetSurfaceMaskLayer, const WebKit::WebFilterOperations& filters)
+void CCDamageTracker::updateDamageTrackingState(const std::vector<CCLayerImpl*>& layerList, int targetSurfaceLayerID, bool targetSurfacePropertyChangedOnlyFromDescendant, const IntRect& targetSurfaceContentRect, CCLayerImpl* targetSurfaceMaskLayer, const WebKit::WebFilterOperations& filters, SkImageFilter* filter)
 {
     //
     // This function computes the "damage rect" of a target surface, and updates the state
@@ -134,8 +134,13 @@ void CCDamageTracker::updateDamageTrackingState(const std::vector<CCLayerImpl*>&
         damageRectForThisUpdate.uniteIfNonZero(damageFromSurfaceMask);
         damageRectForThisUpdate.uniteIfNonZero(damageFromLeftoverRects);
 
-        if (filters.hasFilterThatMovesPixels())
+        if (filters.hasFilterThatMovesPixels()) {
             expandRectWithFilters(damageRectForThisUpdate, filters);
+        } else if (filter) {

[jamesr, 2012/10/22 19:14:17]

Why is this "else"? should we DCHECK() that we don't have stuff in filters and
filter if we don't correctly handle both?

[Stephen White, 2012/10/22 20:11:20]

Yeah, I'll do that. The damage tracker is probably the wrong place, though. 
I'll do it in Layer::setFilter() and setFilters().

[danakj, 2012/10/22 20:12:46]

Can you please also do it in LayerImpl?

[Stephen White, 2012/10/22 21:13:56]

Done.

+            // TODO(senorblanco):  Once SkImageFilter reports its outsets, use
+            // those here to limit damage.
+            damageRectForThisUpdate = targetSurfaceContentRect;
+        }
     }
 
     // Damage accumulates until we are notified that we actually did draw on that frame.