cc: Compute the inflated rect to cover a fixed number of tiles.

cc/tile_priority.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_priority.h"
 
 #include "base/values.h"
 #include "cc/math_util.h"
 
 namespace {
@@ skipping 38 matching lines @@
   else
     out.end_ = std::min(out.end_, t);
 }
 
 }  // namespace
 
 namespace cc {
 
 const float TilePriority::kMaxDistanceInContentSpace = 4096.0f;
 
+// At 256x256 tiles, 80 tiles cover an area of ~1280x4906 pixels.
+const int64 TilePriority::
+    kNumTilesToCoverWithInflatedViewportRectForPrioritization = 80;
+
 scoped_ptr<base::Value> WhichTreeAsValue(WhichTree tree) {
   switch (tree) {
   case ACTIVE_TREE:
       return scoped_ptr<base::Value>(base::Value::CreateStringValue(
           "ACTIVE_TREE"));
   case PENDING_TREE:
       return scoped_ptr<base::Value>(base::Value::CreateStringValue(
           "PENDING_TREE"));
   default:
       DCHECK(false) << "Unrecognized WhichTree value " << tree;
@@ skipping 113 matching lines @@
 scoped_ptr<base::Value> GlobalStateThatImpactsTilePriority::AsValue() const {
   scoped_ptr<base::DictionaryValue> state(new base::DictionaryValue());
   state->Set("memory_limit_policy", TileMemoryLimitPolicyAsValue(memory_limit_policy).release());
   state->SetInteger("memory_limit_in_bytes", memory_limit_in_bytes);
   state->Set("tree_priority", TreePriorityAsValue(tree_priority).release());
   return state.PassAs<base::Value>();
 }
 
 
 }  // namespace cc