cc: Fix hit-testing in zero-opacity layers.

cc/trees/layer_tree_host.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_host.h"
 
 #include <algorithm>
 #include <stack>
 #include <string>
 
@@ skipping 1040 matching lines @@
            LayerIteratorType::Begin(&render_surface_layer_list);
        it != end;
        ++it) {
     bool prevent_occlusion = it.target_render_surface_layer()->HasCopyRequest();
     occlusion_tracker.EnterLayer(it, prevent_occlusion);
 
     if (it.represents_target_render_surface()) {
       PaintMasksForRenderSurface(
           *it, queue, did_paint_content, need_more_updates);
     } else if (it.represents_itself() && it->DrawsContent()) {
-      devtools_instrumentation::ScopedLayerTreeTask
-          update_layer(devtools_instrumentation::kUpdateLayer, it->id(), id());
-      DCHECK(!it->paint_properties().bounds.IsEmpty());
-      *did_paint_content |= it->Update(queue, &occlusion_tracker);
-      *need_more_updates |= it->NeedMoreUpdates();
+      bool zero_opacity = !it->draw_opacity() &&

[enne (OOO), 2013/10/29 23:54:22]

Zero opacity is not the only reason to skip a layer or a subtree.   Can you add
a "visible" draw property that both append quads and update layers can respect? 
It would be set to true if before this patch that layer would end up in the RSLL
(i.e. would be skipped except for input) and false otherwise.

[sadrul, 2013/10/30 15:44:42]

Done (I am calling it 'skip_drawing' to be more like *ShouldBeSkipped()).

+                          !it->draw_opacity_is_animating();
+      if (!zero_opacity) {
+        devtools_instrumentation::ScopedLayerTreeTask update_layer(
+            devtools_instrumentation::kUpdateLayer, it->id(), id());
+        DCHECK(!it->paint_properties().bounds.IsEmpty());
+        *did_paint_content |= it->Update(queue, &occlusion_tracker);
+        *need_more_updates |= it->NeedMoreUpdates();
+      }
     }
 
     occlusion_tracker.LeaveLayer(it);
   }
 
   in_paint_layer_contents_ = false;
 
   occlusion_tracker.overdraw_metrics()->RecordMetrics(this);
 }
 
@@ skipping 208 matching lines @@
 
 bool LayerTreeHost::ScheduleMicroBenchmark(
     const std::string& benchmark_name,
     scoped_ptr<base::Value> value,
     const MicroBenchmark::DoneCallback& callback) {
   return micro_benchmark_controller_.ScheduleRun(
       benchmark_name, value.Pass(), callback);
 }
 
 }  // namespace cc