cc: Ignore offscreen tiles for activation

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 "base/time.h"
 #include "cc/base/math_util.h"
@@ skipping 666 matching lines @@
       high_res = tiling;
       continue;
     }
     for (PictureLayerTiling::CoverageIterator iter(tiling,
                                                    contents_scale_x(),
                                                    rect);
          iter;
          ++iter) {
       if (!*iter || !iter->tile_version().IsReadyToDraw())
         continue;
+
+      // This iteration is over the visible content rect which is potentially
+      // less conservative than projecting the viewport into the layer.
+      // Ignore tiles that are know to be outside the viewport.
+      if (iter->priority(PENDING_TREE).distance_to_visible_in_pixels != 0)
+        continue;
+
       missing_region.Subtract(iter.geometry_rect());
       iter->mark_required_for_activation();
-
-      DCHECK_EQ(iter->priority(PENDING_TREE).distance_to_visible_in_pixels, 0);
-      DCHECK_EQ(iter->priority(PENDING_TREE).time_to_visible_in_seconds, 0);
     }
   }
 
   DCHECK(high_res) << "There must be one high res tiling";
   for (PictureLayerTiling::CoverageIterator iter(high_res,
                                                  contents_scale_x(),
                                                  rect);
        iter;
        ++iter) {
     // A null tile (i.e. missing recording) can just be skipped.
+    if (!*iter)
+      continue;
+
+    // This iteration is over the visible content rect which is potentially
+    // less conservative than projecting the viewport into the layer.
+    // Ignore tiles that are know to be outside the viewport.
+    if (iter->priority(PENDING_TREE).distance_to_visible_in_pixels != 0)
+      continue;
+
     // If the missing region doesn't cover it, this tile is fully
     // covered by acceptable tiles at other scales.
-    if (!*iter || !missing_region.Intersects(iter.geometry_rect()))
+    if (!missing_region.Intersects(iter.geometry_rect()))
       continue;
+
     iter->mark_required_for_activation();
-
-    // These must be true for this tile to end up in the NOW_BIN in TileManager.
-    DCHECK_EQ(iter->priority(PENDING_TREE).distance_to_visible_in_pixels, 0);
-    DCHECK_EQ(iter->priority(PENDING_TREE).time_to_visible_in_seconds, 0);
   }
 }
 
 PictureLayerTiling* PictureLayerImpl::AddTiling(float contents_scale) {
   DCHECK(CanHaveTilingWithScale(contents_scale)) <<
       "contents_scale: " << contents_scale;
 
   PictureLayerTiling* tiling = tilings_->AddTiling(contents_scale);
 
   const Region& recorded = pile_->recorded_region();
@@ skipping 293 matching lines @@
   state->Set("tilings", tilings_->AsValue().release());
   state->Set("pictures", pile_->AsValue().release());
   state->Set("invalidation", invalidation_.AsValue().release());
 }
 
 size_t PictureLayerImpl::GPUMemoryUsageInBytes() const {
   return tilings_->GPUMemoryUsageInBytes();
 }
 
 }  // namespace cc