cc: Stop checking the result of GetInverse in OcclusionTracker.

cc/trees/occlusion_tracker.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/trees/occlusion_tracker.h"
 
 #include <algorithm>
 
 #include "cc/base/math_util.h"
 #include "cc/layers/layer.h"
@@ skipping 501 matching lines @@
 
   DCHECK_EQ(render_target->render_target(), render_target);
   DCHECK(render_target->render_surface());
   DCHECK_EQ(render_target, stack_.back().target);
 
   if (stack_.back().occlusion_from_inside_target.IsEmpty() &&
       stack_.back().occlusion_from_outside_target.IsEmpty()) {
     return false;
   }
 
-  gfx::Transform inverse_draw_transform(gfx::Transform::kSkipInitialization);
-  if (!draw_transform.GetInverse(&inverse_draw_transform))
-    return false;
-
   // Take the ToEnclosingRect at each step, as we want to contain any unoccluded
   // partial pixels in the resulting Rect.
   Region unoccluded_region_in_target_surface =
       MathUtil::MapEnclosingClippedRect(draw_transform, content_rect);
   unoccluded_region_in_target_surface.Subtract(
       stack_.back().occlusion_from_inside_target);
   gfx::RectF unoccluded_rect_in_target_surface_without_outside_occlusion =
       unoccluded_region_in_target_surface.bounds();
   unoccluded_region_in_target_surface.Subtract(
       stack_.back().occlusion_from_outside_target);
@@ skipping 12 matching lines @@
     return content_rect;
   if (content_rect.IsEmpty())
     return content_rect;
 
   if (stack_.back().occlusion_from_inside_target.IsEmpty() &&
       stack_.back().occlusion_from_outside_target.IsEmpty()) {
     return content_rect;
   }
 
   gfx::Transform inverse_draw_transform(gfx::Transform::kSkipInitialization);
-  if (!draw_transform.GetInverse(&inverse_draw_transform))
-    return content_rect;
+  bool ok = draw_transform.GetInverse(&inverse_draw_transform);
+  DCHECK(ok);
 
   // Take the ToEnclosingRect at each step, as we want to contain any unoccluded
   // partial pixels in the resulting Rect.
   Region unoccluded_region_in_target_surface =
       MathUtil::MapEnclosingClippedRect(draw_transform, content_rect);
   unoccluded_region_in_target_surface.Subtract(
       stack_.back().occlusion_from_inside_target);
   unoccluded_region_in_target_surface.Subtract(
       stack_.back().occlusion_from_outside_target);
 
@@ skipping 23 matching lines @@
   if (!has_occlusion)
     return content_rect;
 
   const StackObject& second_last = stack_[stack_.size() - 2];
 
   if (second_last.occlusion_from_inside_target.IsEmpty() &&
       second_last.occlusion_from_outside_target.IsEmpty())
     return content_rect;
 
   gfx::Transform inverse_draw_transform(gfx::Transform::kSkipInitialization);
-  if (!draw_transform.GetInverse(&inverse_draw_transform))
-    return content_rect;
+  bool ok = draw_transform.GetInverse(&inverse_draw_transform);
+  DCHECK(ok);
 
   // Take the ToEnclosingRect at each step, as we want to contain any unoccluded
   // partial pixels in the resulting Rect.
   Region unoccluded_region_in_target_surface =
       MathUtil::MapEnclosingClippedRect(draw_transform, content_rect);
   unoccluded_region_in_target_surface.Subtract(
       second_last.occlusion_from_inside_target);
   unoccluded_region_in_target_surface.Subtract(
       second_last.occlusion_from_outside_target);
 
   if (unoccluded_region_in_target_surface.IsEmpty())
     return gfx::Rect();
 
   gfx::Rect unoccluded_rect_in_target_surface =
       unoccluded_region_in_target_surface.bounds();
   gfx::Rect unoccluded_rect = MathUtil::ProjectEnclosingClippedRect(
       inverse_draw_transform, unoccluded_rect_in_target_surface);
   unoccluded_rect.Intersect(content_rect);
 
   return unoccluded_rect;
 }
 
 // Instantiate (and export) templates here for the linker.
 template class OcclusionTracker<Layer>;
 template class OcclusionTracker<LayerImpl>;
 
 }  // namespace cc