cc: Make corner cases of tile priority computation more simple.

cc/tiles/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/tiles/picture_layer_tiling.h"
 
 #include <algorithm>
 #include <cmath>
 #include <limits>
 #include <set>
@@ skipping 827 matching lines @@
         MakePrioritizedTile(tile, ComputePriorityRectTypeForTile(tile));
     result.insert(std::make_pair(prioritized_tile.tile(), prioritized_tile));
   }
   return result;
 }
 
 TilePriority PictureLayerTiling::ComputePriorityForTile(
     const Tile* tile,
     PriorityRectType priority_rect_type) const {
   // TODO(vmpstr): See if this can be moved to iterators.
-  TilePriority::PriorityBin max_tile_priority_bin =
-      client_->GetMaxTilePriorityBin();
-
   DCHECK_EQ(ComputePriorityRectTypeForTile(tile), priority_rect_type);
   DCHECK_EQ(TileAt(tile->tiling_i_index(), tile->tiling_j_index()), tile);
 
-  TilePriority::PriorityBin priority_bin = max_tile_priority_bin;
+  TilePriority::PriorityBin priority_bin = client_->GetMaxTilePriorityBin();
 
   switch (priority_rect_type) {
     case VISIBLE_RECT:
       return TilePriority(resolution_, priority_bin, 0);
     case PENDING_VISIBLE_RECT:
-      if (max_tile_priority_bin <= TilePriority::SOON)
-        return TilePriority(resolution_, TilePriority::SOON, 0);
-      priority_bin = TilePriority::EVENTUALLY;
-      break;
+      if (priority_bin < TilePriority::SOON)
+        priority_bin = TilePriority::SOON;
+      return TilePriority(resolution_, priority_bin, 0);
     case SKEWPORT_RECT:
     case SOON_BORDER_RECT:
-      if (max_tile_priority_bin <= TilePriority::SOON)
+      if (priority_bin < TilePriority::SOON)
         priority_bin = TilePriority::SOON;
       break;
     case EVENTUALLY_RECT:
       priority_bin = TilePriority::EVENTUALLY;
       break;
   }
 
   gfx::Rect tile_bounds =
       tiling_data_.TileBounds(tile->tiling_i_index(), tile->tiling_j_index());
   DCHECK_GT(current_content_to_screen_scale_, 0.f);
@@ skipping 201 matching lines @@
       break;
   }
 
   gfx::Rect result(origin_x, origin_y, width, height);
   if (cache)
     cache->previous_result = result;
   return result;
 }
 
 }  // namespace cc