cc: Don't DCHECK for layers with non-invertible transforms.

cc/resources/picture_layer_tiling.cc

 // Copyright 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "cc/resources/picture_layer_tiling.h"
 
 #include <algorithm>
 #include <cmath>
 
 #include "base/debug/trace_event.h"
@@ skipping 508 matching lines @@
 struct EdgeEvent {
   enum { BOTTOM, TOP, LEFT, RIGHT } edge;
   int* num_edges;
   int distance;
 };
 
 gfx::Rect PictureLayerTiling::ExpandRectEquallyToAreaBoundedBy(
     gfx::Rect starting_rect,
     int64 target_area,
     gfx::Rect bounding_rect) {
-  DCHECK(!starting_rect.IsEmpty());
+  if (starting_rect.IsEmpty())
+    return starting_rect;
+
   DCHECK(!bounding_rect.IsEmpty());
   DCHECK_GT(target_area, 0);
 
   gfx::Rect rect = IntersectRects(starting_rect, bounding_rect);
   if (rect.IsEmpty())
     return rect;
 
   // These values will be updated by the loop and uses as the output.
   int origin_x = rect.x();
   int origin_y = rect.y();
@@ skipping 68 matching lines @@
 
     // If our delta is less then our event distance, we're done.
     if (delta < event.distance)
       break;
   }
 
   return gfx::Rect(origin_x, origin_y, width, height);
 }
 
 }  // namespace cc