Preliminary compositor disabling patch.

cc/trees/layer_tree_host_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_host_impl.h"
 
 #include <algorithm>
 #include <limits>
 
 #include "base/basictypes.h"
@@ skipping 672 matching lines @@
   DCHECK(CanDraw());
   DCHECK(active_tree_->root_layer());
 
   TrackDamageForAllSurfaces(active_tree_->root_layer(),
                             *frame->render_surface_layer_list);
 
   // If the root render surface has no visible damage, then don't generate a
   // frame at all.
   RenderSurfaceImpl* root_surface =
       active_tree_->root_layer()->render_surface();
+  gfx::Rect damage_rect_with_overlays =
+      gfx::UnionRects(root_surface->damage_tracker()->current_damage_rect(),
+                      root_surface->damage_tracker()->current_overlay_rect());
   bool root_surface_has_no_visible_damage =
-      !root_surface->damage_tracker()->current_damage_rect().Intersects(
-          root_surface->content_rect());
-  bool root_surface_has_contributing_layers =
+      !damage_rect_with_overlays.Intersects(root_surface->content_rect());
+  bool root_surface_has_no_contributing_layers =
       !root_surface->layer_list().empty();
   bool hud_wants_to_draw_ = active_tree_->hud_layer() &&
                             active_tree_->hud_layer()->IsAnimatingHUDContents();
-  if (root_surface_has_contributing_layers &&
+  if (root_surface_has_no_contributing_layers &&
       root_surface_has_no_visible_damage &&
       active_tree_->LayersWithCopyOutputRequest().empty() &&
       !output_surface_->capabilities().can_force_reclaim_resources &&
       !hud_wants_to_draw_) {
     TRACE_EVENT0("cc",
                  "LayerTreeHostImpl::CalculateRenderPasses::EmptyDamageRect");
     frame->has_no_damage = true;
     DCHECK(!output_surface_->capabilities()
                .draw_and_swap_full_viewport_every_frame);
     return DRAW_SUCCESS;
@@ skipping 181 matching lines @@
 
   if (!active_tree_->has_transparent_background()) {
     frame->render_passes.back()->has_transparent_background = false;
     AppendQuadsToFillScreen(
         active_tree_->RootScrollLayerDeviceViewportBounds(),
         frame->render_passes.back(), active_tree_->root_layer(),
         active_tree_->background_color(), unoccluded_screen_space_region);
   }
 
   RemoveRenderPasses(CullRenderPassesWithNoQuads(), frame);
+
+  // Only the root render pass is allowed to have overlays, so we can merge
+  // in all quad damage for the other ones now.
+  for (size_t i = 0; i < frame->render_passes.size() - 1; ++i) {
+    RenderPass* pass = frame->render_passes.at(i);
+    pass->damage_rect.Union(pass->overlay_rect);
+    pass->overlay_rect = gfx::Rect();
+  }
+
   renderer_->DecideRenderPassAllocationsForFrame(frame->render_passes);
 
   // Any copy requests left in the tree are not going to get serviced, and
   // should be aborted.
   ScopedPtrVector<CopyOutputRequest> requests_to_abort;
   while (!active_tree_->LayersWithCopyOutputRequest().empty()) {
     LayerImpl* layer = active_tree_->LayersWithCopyOutputRequest().back();
     layer->TakeCopyRequestsAndTransformToTarget(&requests_to_abort);
   }
   for (size_t i = 0; i < requests_to_abort.size(); ++i)
@@ skipping 2555 matching lines @@
   new_target.SetToMin(layer_impl->MaxScrollOffset());
 
   curve->UpdateTarget(
       animation->TrimTimeToCurrentIteration(CurrentBeginFrameArgs().frame_time)
           .InSecondsF(),
       new_target);
 
   return true;
 }
 }  // namespace cc