cc: Calculate "can use lcd text" on the compositor thread

cc/trees/layer_tree_impl.cc

 // Copyright 2011 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/trees/layer_tree_impl.h"
 
 #include <algorithm>
 #include <limits>
 #include <set>
 
@@ skipping 63 matching lines @@
   gfx::ScrollOffset last_set_scroll_offset_;
 };
 
 LayerTreeImpl::LayerTreeImpl(
     LayerTreeHostImpl* layer_tree_host_impl,
     scoped_refptr<SyncedProperty<ScaleGroup>> page_scale_factor,
     scoped_refptr<SyncedTopControls> top_controls_shown_ratio,
     scoped_refptr<SyncedElasticOverscroll> elastic_overscroll)
     : layer_tree_host_impl_(layer_tree_host_impl),
       source_frame_number_(-1),
+      last_update_draw_properties_frame_number_(-1),
       hud_layer_(0),
       currently_scrolling_layer_(NULL),
       root_layer_scroll_offset_delegate_(NULL),
       background_color_(0),
       has_transparent_background_(false),
       overscroll_elasticity_layer_(NULL),
       page_scale_layer_(NULL),
       inner_viewport_scroll_layer_(NULL),
       outer_viewport_scroll_layer_(NULL),
       page_scale_factor_(page_scale_factor),
@@ skipping 481 matching lines @@
 
   {
     TRACE_EVENT2("cc", "LayerTreeImpl::UpdateDrawProperties::Occlusion",
                  "IsActive", IsActiveTree(), "SourceFrameNumber",
                  source_frame_number_);
     OcclusionTracker<LayerImpl> occlusion_tracker(
         root_layer()->render_surface()->content_rect());
     occlusion_tracker.set_minimum_tracking_size(
         settings().minimum_occlusion_tracking_size);
 
+    // It'd be ideal if this could be done earlier, but when the raster source

[danakj, 2015/02/18 01:25:52]

Can you move this out of the ::Occlusion {}? Maybe down with UpdateTiles?

[enne (OOO), 2015/02/18 19:43:05]

Done.

+    // is updated from the main thread during push properties, update draw
+    // properties has not occurred yet and so it's not clear whether or not the
+    // layer can or cannot use lcd text.  So, this is the cleanup pass to
+    // determine if the raster source needs to be replaced with a non-lcd
+    // raster source due to draw properties.
+    //
+    // TODO(enne): Make LTHI::sync_tree return this value.
+    LayerTreeImpl* sync_tree =
+        layer_tree_host_impl_->proxy()->CommitToActiveTree()
+            ? layer_tree_host_impl_->active_tree()
+            : layer_tree_host_impl_->pending_tree();
+    if (this == sync_tree &&
+        source_frame_number_ != last_update_draw_properties_frame_number_) {
+      for (const auto& layer : picture_layers_)
+        layer->UpdateCanUseLCDText();
+    }
+    last_update_draw_properties_frame_number_ = source_frame_number_;
+
     // LayerIterator is used here instead of CallFunctionForSubtree to only
     // UpdateTilePriorities on layers that will be visible (and thus have valid
     // draw properties) and not because any ordering is required.
     auto end = LayerIterator<LayerImpl>::End(&render_surface_layer_list_);
     for (auto it = LayerIterator<LayerImpl>::Begin(&render_surface_layer_list_);
          it != end; ++it) {
       occlusion_tracker.EnterLayer(it);
 
       // There are very few render targets so this should be cheap to do for
       // each layer instead of something more complicated.
@@ skipping 1026 matching lines @@
     scoped_ptr<PendingPageScaleAnimation> pending_animation) {
   pending_page_scale_animation_ = pending_animation.Pass();
 }
 
 scoped_ptr<PendingPageScaleAnimation>
     LayerTreeImpl::TakePendingPageScaleAnimation() {
   return pending_page_scale_animation_.Pass();
 }
 
 }  // namespace cc