cc: Handle overflow/underflow in MathUtil::RoundUp/RoundDown functions.

cc/layers/picture_layer_impl.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/layers/picture_layer_impl.h"
 
 #include <algorithm>
 #include <cmath>
 #include <limits>
 #include <set>
@@ skipping 684 matching lines @@
     int viewport_height = gpu_raster_max_texture_size_.height();
     default_tile_width = viewport_width;
 
     // Also, increase the height proportionally as the width decreases, and
     // pad by our border texels to make the tiles exactly match the viewport.
     int divisor = 4;
     if (content_bounds.width() <= viewport_width / 2)
       divisor = 2;
     if (content_bounds.width() <= viewport_width / 4)
       divisor = 1;
-    default_tile_height = MathUtil::RoundUp(viewport_height, divisor) / divisor;
+    default_tile_height =
+        MathUtil::UncheckedRoundUp(viewport_height, divisor) / divisor;
 
     // Grow default sizes to account for overlapping border texels.
     default_tile_width += 2 * PictureLayerTiling::kBorderTexels;
     default_tile_height += 2 * PictureLayerTiling::kBorderTexels;
 
     default_tile_height =
         std::max(default_tile_height, kMinHeightForGpuRasteredTile);
   } else {
     // For CPU rasterization we use tile-size settings.
     const LayerTreeSettings& settings = layer_tree_impl()->settings();
@@ skipping 15 matching lines @@
       default_tile_width = max_untiled_content_width;
     }
   }
 
   int tile_width = default_tile_width;
   int tile_height = default_tile_height;
 
   // Clamp the tile width/height to the content width/height to save space.
   if (content_bounds.width() < default_tile_width) {
     tile_width = std::min(tile_width, content_bounds.width());
-    tile_width = MathUtil::RoundUp(tile_width, kTileRoundUp);
+    tile_width = MathUtil::UncheckedRoundUp(tile_width, kTileRoundUp);
     tile_width = std::min(tile_width, default_tile_width);
   }
   if (content_bounds.height() < default_tile_height) {
     tile_height = std::min(tile_height, content_bounds.height());
-    tile_height = MathUtil::RoundUp(tile_height, kTileRoundUp);
+    tile_height = MathUtil::UncheckedRoundUp(tile_height, kTileRoundUp);
     tile_height = std::min(tile_height, default_tile_height);
   }
 
   // Under no circumstance should we be larger than the max texture size.
   tile_width = std::min(tile_width, max_texture_size);
   tile_height = std::min(tile_height, max_texture_size);
   return gfx::Size(tile_width, tile_height);
 }
 
 void PictureLayerImpl::GetContentsResourceId(ResourceId* resource_id,
@@ skipping 469 matching lines @@
 
 bool PictureLayerImpl::IsOnActiveOrPendingTree() const {
   return !layer_tree_impl()->IsRecycleTree();
 }
 
 bool PictureLayerImpl::HasValidTilePriorities() const {
   return IsOnActiveOrPendingTree() && IsDrawnRenderSurfaceLayerListMember();
 }
 
 }  // namespace cc