cc: disable denorm handling before calling into Skia's filter code.

cc/output/software_renderer.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/output/software_renderer.h"
 
 #include "base/memory/ptr_util.h"
 #include "base/trace_event/trace_event.h"
 #include "cc/base/math_util.h"
 #include "cc/output/compositor_frame.h"
@@ skipping 660 matching lines @@
 
   SkImageInfo dst_info =
       SkImageInfo::MakeN32Premul(dst_rect.width(), dst_rect.height());
   sk_sp<SkSurface> surface = SkSurface::MakeRaster(dst_info);
 
   if (!surface) {
     return nullptr;
   }
 
   SkPaint paint;
+  // Treat subnormal float values as zero for performance.
+  ScopedSubnormalFloatDisabler disabler;
   paint.setImageFilter(filter->makeWithLocalMatrix(local_matrix));
   surface->getCanvas()->translate(-dst_rect.x(), -dst_rect.y());
   surface->getCanvas()->drawBitmap(to_filter, quad->rect.x(), quad->rect.y(),
                                    &paint);
 
   return surface->makeImageSnapshot();
 }
 
 SkBitmap SoftwareRenderer::GetBackdropBitmap(
     const gfx::Rect& bounding_rect) const {
@@ skipping 60 matching lines @@
       ApplyImageFilter(filter.get(), quad, backdrop_bitmap, nullptr);
 
   if (!filter_backdrop_image)
     return nullptr;
 
   return filter_backdrop_image->makeShader(content_tile_mode, content_tile_mode,
                                            &filter_backdrop_transform);
 }
 
 }  // namespace cc