cc: Don't discard tiles unless memory is low

cc/tile_manager.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/tile_manager.h"
 
 #include <algorithm>
 
 #include "base/bind.h"
 #include "base/debug/trace_event.h"
@@ skipping 30 matching lines @@
 // Determine bin based on three categories of tiles: things we need now,
 // things we need soon, and eventually.
 inline TileManagerBin BinFromTilePriority(const TilePriority& prio) {
   if (!prio.is_live)
     return NEVER_BIN;
 
   // The amount of time for which we want to have prepainting coverage.
   const double prepainting_window_time_seconds = 1.0;
   const double backfling_guard_distance_pixels = 314.0;
 
-  // Explicitly limit how far ahead we will prepaint to limit memory usage.
-  if (prio.distance_to_visible_in_pixels >
-      TilePriority::kMaxDistanceInContentSpace)
-    return NEVER_BIN;
-
   if (prio.time_to_visible_in_seconds == 0 ||
       prio.distance_to_visible_in_pixels < backfling_guard_distance_pixels)
     return NOW_BIN;
 
   if (prio.resolution == NON_IDEAL_RESOLUTION)
     return EVENTUALLY_BIN;
 
   if (prio.time_to_visible_in_seconds < prepainting_window_time_seconds)
     return SOON_BIN;
 
@@ skipping 930 matching lines @@
     decode_begin_time = base::TimeTicks::HighResNow();
   pixel_ref->Decode();
   if (stats) {
     stats->totalDeferredImageDecodeCount++;
     stats->totalDeferredImageDecodeTime +=
         base::TimeTicks::HighResNow() - decode_begin_time;
   }
 }
 
 }  // namespace cc