Bug 777194. Part 2: Remove RETENTION_THRESHOLD. FrameLayerBuilder limits the complexity of visible regions anyway. r=bas

gfx/layers/d3d10/ThebesLayerD3D10.cpp

@@ -42,15 +42,7 @@ ThebesLayerD3D10::~ThebesLayerD3D10()
 {
 }
 
-/**
- * Retention threshold - amount of pixels intersection required to enable
- * layer content retention. This is a guesstimate. Profiling could be done to
- * figure out the optimal threshold.
- */
-#define RETENTION_THRESHOLD 16384
-
 void
-
 ThebesLayerD3D10::InvalidateRegion(const nsIntRegion &aRegion)
 {
   mValidRegion.Sub(mValidRegion, aRegion);
@@ -64,7 +56,6 @@ void ThebesLayerD3D10::CopyRegion(ID3D10Texture2D* aSrc, const nsIntPoint &aSrcO
   nsIntRegionRectIterator iter(aCopyRegion);
   const nsIntRect *r;
   while ((r = iter.Next())) {
-    if (r->width * r->height > RETENTION_THRESHOLD) {
     // Calculate the retained rectangle's position on the old and the new
     // surface.
     D3D10_BOX box;
@@ -84,7 +75,6 @@ void ThebesLayerD3D10::CopyRegion(ID3D10Texture2D* aSrc, const nsIntPoint &aSrcO
 
     retainedRegion.Or(retainedRegion, *r);
   }
-  }
 
   // Areas which were valid and were retained are still valid
   aValidRegion->And(*aValidRegion, retainedRegion);  
@@ -219,8 +209,7 @@ ThebesLayerD3D10::Validate(ReadbackProcessor *aReadback)
       // and we should silently ignore the failure. In the future when device
       // failures are properly handled we should test for the type of failure
       // and gracefully handle different failures. See bug 569081.
-      if (!oldTexture || !mTexture ||
-          largeRect.width * largeRect.height < RETENTION_THRESHOLD) {
+      if (!oldTexture || !mTexture) {
         mValidRegion.SetEmpty();
       } else {
         CopyRegion(oldTexture, mTextureRect.TopLeft(),