cc: Make tiles that are not required by trees NEVER_BIN

cc/resources/tile_priority.h

 // 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.
 
 #ifndef CC_RESOURCES_TILE_PRIORITY_H_
 #define CC_RESOURCES_TILE_PRIORITY_H_
 
 #include <algorithm>
 #include <limits>
 
@@ skipping 27 matching lines @@
   NON_IDEAL_RESOLUTION = 2,
 };
 scoped_ptr<base::Value> TileResolutionAsValue(
     TileResolution resolution);
 
 struct CC_EXPORT TilePriority {
   TilePriority()
       : resolution(NON_IDEAL_RESOLUTION),
         required_for_activation(false),
         time_to_visible_in_seconds(std::numeric_limits<float>::infinity()),
-        distance_to_visible_in_pixels(std::numeric_limits<float>::infinity()) {}
+        distance_to_visible_in_pixels(std::numeric_limits<float>::infinity()),
+        required_by_tree(false) {}
 
   TilePriority(TileResolution resolution,
                float time_to_visible_in_seconds,
                float distance_to_visible_in_pixels)
       : resolution(resolution),
         required_for_activation(false),
         time_to_visible_in_seconds(time_to_visible_in_seconds),
-        distance_to_visible_in_pixels(distance_to_visible_in_pixels) {}
+        distance_to_visible_in_pixels(distance_to_visible_in_pixels),
+        required_by_tree(true) {}
 
   TilePriority(const TilePriority& active, const TilePriority& pending) {
     if (active.resolution == HIGH_RESOLUTION ||
         pending.resolution == HIGH_RESOLUTION)
       resolution = HIGH_RESOLUTION;
     else if (active.resolution == LOW_RESOLUTION ||
              pending.resolution == LOW_RESOLUTION)
       resolution = LOW_RESOLUTION;
     else
       resolution = NON_IDEAL_RESOLUTION;
 
     required_for_activation =
         active.required_for_activation || pending.required_for_activation;
 
     time_to_visible_in_seconds =
       std::min(active.time_to_visible_in_seconds,
                pending.time_to_visible_in_seconds);
     distance_to_visible_in_pixels =
       std::min(active.distance_to_visible_in_pixels,
                pending.distance_to_visible_in_pixels);
+
+    required_by_tree =
+        active.required_by_tree || pending.required_by_tree;
   }
   void set_current_screen_quad(const gfx::QuadF& q) { current_screen_quad = q; }
 
   scoped_ptr<base::Value> AsValue() const;
 
   static inline float manhattanDistance(const gfx::RectF& a,
                                         const gfx::RectF& b) {
     // Compute the union explicitly.
     gfx::RectF c = gfx::RectF(
         std::min(a.x(), b.x()),
@@ skipping 25 matching lines @@
   }
 
   bool operator !=(const TilePriority& other) const {
     return !(*this == other);
   }
 
   TileResolution resolution;
   bool required_for_activation;
   float time_to_visible_in_seconds;
   float distance_to_visible_in_pixels;
+  bool required_by_tree;
 
  private:
   gfx::QuadF current_screen_quad;
 };
 
 enum TileMemoryLimitPolicy {
   // Nothing.
   ALLOW_NOTHING,
 
   // You might be made visible, but you're not being interacted with.
@@ skipping 33 matching lines @@
   size_t unused_memory_limit_in_bytes;
 
   TreePriority tree_priority;
 
   scoped_ptr<base::Value> AsValue() const;
 };
 
 }  // namespace cc
 
 #endif  // CC_RESOURCES_TILE_PRIORITY_H_