cc: Simplify picture layer tiling update tile priorities.

cc/resources/tile_manager.cc

Index: cc/resources/tile_manager.cc
diff --git a/cc/resources/tile_manager.cc b/cc/resources/tile_manager.cc
index 4f9f0aed6545b1792c93111f34313194c1268288..e769d5f465f8d9f806afbc9516254e4ac8100ee3 100644
--- a/cc/resources/tile_manager.cc
+++ b/cc/resources/tile_manager.cc
@@ -115,38 +115,16 @@ const ManagedTileBin kBinIsActiveMap[2][NUM_BINS] = {
 // Determine bin based on three categories of tiles: things we need now,
 // things we need soon, and eventually.
 inline ManagedTileBin BinFromTilePriority(const TilePriority& prio) {
-  // The amount of time/pixels for which we want to have prepainting coverage.
-  // Note: All very arbitrary constants: metric-based tuning is welcome!
-  const float kPrepaintingWindowTimeSeconds = 1.0f;

[enne (OOO), 2014/01/31 23:07:46]

Should the soon bin skewport window be 1 second instead of 0.5 to try to
minimize behavior changes in this patch?

[vmpstr, 2014/02/03 20:27:24]

Done.

-  const float kBackflingGuardDistancePixels = 314.0f;

[vmpstr, 2014/01/31 20:53:38]

Note that this patch eliminates backfling thing. We can add it back using some
skewport adjustments. However, all tiles outside of the viewport will now be
marked as eventually and sorted by distance, so they should be higher priority
than other non-skewport tiles.

-  // Note: The max distances here assume that SOON_BIN will never help overcome
-  // raster being too slow (only caching in advance will do that), so we just
-  // need enough padding to handle some latency and per-tile variability.
-  const float kMaxPrepaintingDistancePixelsHighRes = 2000.0f;
-  const float kMaxPrepaintingDistancePixelsLowRes = 4000.0f;
-
-  if (prio.distance_to_visible_in_pixels ==
-      std::numeric_limits<float>::infinity())
-    return NEVER_BIN;
-
-  if (prio.time_to_visible_in_seconds == 0)
+  if (prio.priority_bin == TilePriority::NOW)
     return NOW_BIN;
 
-  if (prio.resolution == NON_IDEAL_RESOLUTION)
-    return EVENTUALLY_BIN;
-
-  float max_prepainting_distance_pixels =
-      (prio.resolution == HIGH_RESOLUTION)
-          ? kMaxPrepaintingDistancePixelsHighRes
-          : kMaxPrepaintingDistancePixelsLowRes;
-
-  // Soon bin if we are within backfling-guard, or under both the time window
-  // and the max distance window.
-  if (prio.distance_to_visible_in_pixels < kBackflingGuardDistancePixels ||
-      (prio.time_to_visible_in_seconds < kPrepaintingWindowTimeSeconds &&
-       prio.distance_to_visible_in_pixels <= max_prepainting_distance_pixels))
+  if (prio.priority_bin == TilePriority::SOON)
     return SOON_BIN;
 
+  if (prio.distance_to_visible ==

[enne (OOO), 2014/01/31 23:07:46]

When does this happen?

[vmpstr, 2014/02/03 20:27:24]

This is magic :P. distance_to_visible == inf means that we cleared that tile's
priority to default which means that we haven't updated tile priorities which
means it's an active tree priority for a tile only on the pending tree, or maybe
something on the recycle tree.

If you look at around 425-426 in this file, we still keep the tile around if it
was prioritized on one of the trees but at the lowest priority.

+      std::numeric_limits<float>::infinity())
+    return NEVER_BIN;
+
   return EVENTUALLY_BIN;
 }
 
@@ -448,9 +426,9 @@ void TileManager::GetTilesWithAssignedBins(PrioritizedTileSet* tiles) {
       mts.bin = tile_is_active ? AT_LAST_AND_ACTIVE_BIN : AT_LAST_BIN;
 
     mts.resolution = tile_priority.resolution;
-    mts.time_to_needed_in_seconds = tile_priority.time_to_visible_in_seconds;
-    mts.distance_to_visible_in_pixels =
-        tile_priority.distance_to_visible_in_pixels;
+    mts.priority_bin = tile_priority.priority_bin;
+    mts.distance_to_visible =
+        tile_priority.distance_to_visible;
     mts.required_for_activation = tile_priority.required_for_activation;
 
     mts.visible_and_ready_to_draw =
@@ -952,7 +930,7 @@ void TileManager::OnRasterTaskCompleted(
   }
 
   FreeUnusedResourcesForTile(tile);
-  if (tile->priority(ACTIVE_TREE).distance_to_visible_in_pixels == 0)
+  if (tile->priority(ACTIVE_TREE).distance_to_visible == 0)

[enne (OOO), 2014/01/31 23:07:46]

style nit: 0.f

[vmpstr, 2014/02/03 20:27:24]

Done.

     did_initialize_visible_tile_ = true;
 }