cc: Removed DCHECK that asserted MapPoint returns clipped as true

cc/output/gl_renderer.cc

 // Copyright 2010 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/output/gl_renderer.h"
 
 #include <algorithm>
 #include <limits>
 #include <set>
 #include <string>
@@ skipping 1404 matching lines @@
 
   device_layer_edges.ToFloatArray(edge);
   device_layer_bounds.ToFloatArray(&edge[12]);
 
   gfx::PointF bottom_right = tile_rect.bottom_right();
   gfx::PointF bottom_left = tile_rect.bottom_left();
   gfx::PointF top_left = tile_rect.origin();
   gfx::PointF top_right = tile_rect.top_right();
 
   // Map points to device space.
   bottom_right = MathUtil::MapPoint(device_transform, bottom_right, &clipped);

[danakj, 2014/09/26 23:04:34]

can you add comment explaining why we are ignoring the clipped value here and
point it at the bug

-  DCHECK(!clipped);

[danakj, 2014/09/26 21:09:19]

If it's clipped then the coordinates returned by MapPoint are not valid:
https://code.google.com/p/chromium/codesearch#chromium/src/cc/base/math_util....

   bottom_left = MathUtil::MapPoint(device_transform, bottom_left, &clipped);
-  DCHECK(!clipped);
   top_left = MathUtil::MapPoint(device_transform, top_left, &clipped);
-  DCHECK(!clipped);
   top_right = MathUtil::MapPoint(device_transform, top_right, &clipped);
-  DCHECK(!clipped);
 
   LayerQuad::Edge bottom_edge(bottom_right, bottom_left);
   LayerQuad::Edge left_edge(bottom_left, top_left);
   LayerQuad::Edge top_edge(top_left, top_right);
   LayerQuad::Edge right_edge(top_right, bottom_right);
 
   // Only apply anti-aliasing to edges not clipped by culling or scissoring.
   if (quad->IsTopEdge() && tile_rect.y() == quad->rect.y())
     top_edge = device_layer_edges.top();
   if (quad->IsLeftEdge() && tile_rect.x() == quad->rect.x())
@@ skipping 1759 matching lines @@
     context_support_->ScheduleOverlayPlane(
         overlay.plane_z_order,
         overlay.transform,
         pending_overlay_resources_.back()->texture_id(),
         overlay.display_rect,
         overlay.uv_rect);
   }
 }
 
 }  // namespace cc