cc: Add some debugging info to failing DCHECK in PictureLayerTilingSet

cc/resources/picture_layer_tiling_set.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/resources/picture_layer_tiling_set.h"
 
 #include <limits>
 #include <set>
 #include <vector>
 
@@ skipping 105 matching lines @@
   }
 
   if (!tilings_.empty()) {
     size_t num_high_res = std::count_if(tilings_.begin(), tilings_.end(),
                                         [](PictureLayerTiling* tiling) {
       return tiling->resolution() == HIGH_RESOLUTION;
     });
     DCHECK_LE(num_high_res, 1u);
     // When commiting from the main thread the high res tiling may get dropped,
     // but when cloning to the active tree, there should always be one.
     if (twin_set)

[vmpstr, 2015/02/05 18:26:33]

nit: wrap in braces please

[danakj, 2015/02/05 18:32:03]

Done.

-      DCHECK_EQ(1u, num_high_res);
+      DCHECK_EQ(1u, num_high_res)
+          << " num tilings on active: " << tilings_.size()

[vmpstr, 2015/02/05 18:26:33]

Maybe also tilings_->NumHighResTilings() for both this and twin?

[danakj, 2015/02/05 18:32:03]

Done.

+          << " num tilings on pending: " << twin_set->tilings_.size()
+          << " are on active tree: " << (client_->GetTree() == ACTIVE_TREE);
   }
 #endif
 }
 
 void PictureLayerTilingSet::CleanUpTilings(
     float min_acceptable_high_res_scale,
     float max_acceptable_high_res_scale,
     const std::vector<PictureLayerTiling*>& needed_tilings,
     bool should_have_low_res,
     PictureLayerTilingSet* twin_set,
@@ skipping 398 matching lines @@
     case LOWER_THAN_LOW_RES:
       range = TilingRange(low_res_range.end, tilings_.size());
       break;
   }
 
   DCHECK_LE(range.start, range.end);
   return range;
 }
 
 }  // namespace cc