cc: Simplify picture layer tiling update tile priorities.

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 23 matching lines @@
 
 enum TileResolution {
   LOW_RESOLUTION = 0 ,
   HIGH_RESOLUTION = 1,
   NON_IDEAL_RESOLUTION = 2,
 };
 scoped_ptr<base::Value> TileResolutionAsValue(
     TileResolution resolution);
 
 struct CC_EXPORT TilePriority {
+  enum PriorityBin { NOW, SOON, EVENTUALLY };
+
   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()) {}
+        priority_bin(EVENTUALLY),
+        distance_to_visible(std::numeric_limits<float>::infinity()) {}
 
   TilePriority(TileResolution resolution,
-               float time_to_visible_in_seconds,
-               float distance_to_visible_in_pixels)
+               PriorityBin bin,
+               float distance_to_visible)
       : 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) {}
+        priority_bin(bin),
+        distance_to_visible(distance_to_visible) {}
 
   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);
+    if (active.priority_bin < pending.priority_bin) {
+      priority_bin = active.priority_bin;
+      distance_to_visible = active.distance_to_visible;
+    } else if (active.priority_bin > pending.priority_bin) {
+      priority_bin = pending.priority_bin;
+      distance_to_visible = pending.distance_to_visible;
+    } else {
+      priority_bin = active.priority_bin;
+      distance_to_visible =
+          std::min(active.distance_to_visible, pending.distance_to_visible);
+    }
   }
 
   scoped_ptr<base::Value> AsValue() const;
 
-  // Calculate the time for the |current_bounds| to intersect with the
-  // |target_bounds| given its previous location and time delta.
-  // This function should work for both scaling and scrolling case.
-  static float TimeForBoundsToIntersect(const gfx::RectF& previous_bounds,
-                                        const gfx::RectF& current_bounds,
-                                        float time_delta,
-                                        const gfx::RectF& target_bounds);
-
   bool operator ==(const TilePriority& other) const {
     return resolution == other.resolution &&
-        time_to_visible_in_seconds == other.time_to_visible_in_seconds &&
-        distance_to_visible_in_pixels == other.distance_to_visible_in_pixels &&
-        required_for_activation == other.required_for_activation;
+           priority_bin == other.priority_bin &&
+           distance_to_visible == other.distance_to_visible &&
+           required_for_activation == other.required_for_activation;
   }
 
   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;
+  PriorityBin priority_bin;
+  float distance_to_visible;
 };
 
+scoped_ptr<base::Value> TilePriorityBinAsValue(TilePriority::PriorityBin bin);
+
 enum TileMemoryLimitPolicy {
   // Nothing.
   ALLOW_NOTHING = 0,
 
   // You might be made visible, but you're not being interacted with.
   ALLOW_ABSOLUTE_MINIMUM = 1,  // Tall.
 
   // You're being interacted with, but we're low on memory.
   ALLOW_PREPAINT_ONLY = 2,  // Grande.
 
@@ skipping 44 matching lines @@
   bool operator!=(const GlobalStateThatImpactsTilePriority& other) const {
     return !(*this == other);
   }
 
   scoped_ptr<base::Value> AsValue() const;
 };
 
 }  // namespace cc
 
 #endif  // CC_RESOURCES_TILE_PRIORITY_H_