Mac Overlays: Allow multiple overlays with sandwich strategy

cc/output/overlay_strategy_underlay.cc

 // Copyright 2014 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/output/overlay_strategy_underlay.h"
 
 #include "cc/output/overlay_candidate_validator.h"
 #include "cc/quads/draw_quad.h"
 #include "cc/quads/solid_color_draw_quad.h"
 
 namespace cc {
 
 OverlayStrategyUnderlay::~OverlayStrategyUnderlay() {}
 
-bool OverlayStrategyUnderlay::TryOverlay(
+OverlayResult OverlayStrategyUnderlay::TryOverlay(
     OverlayCandidateValidator* capability_checker,
     RenderPassList* render_passes_in_draw_order,
     OverlayCandidateList* candidate_list,
     const OverlayCandidate& candidate,
-    QuadList::Iterator candidate_iterator,
+    QuadList::Iterator* candidate_iterator,
     float device_scale_factor) {
   RenderPass* root_render_pass = render_passes_in_draw_order->back();
   QuadList& quad_list = root_render_pass->quad_list;
 
-  // Add our primary surface.
-  OverlayCandidateList candidates;
-  OverlayCandidate main_image;
-  main_image.display_rect = root_render_pass->output_rect;
-  candidates.push_back(main_image);
-
   // Add the overlay.

[ccameron, 2015/09/08 17:16:06]

(same as before)
Might be clearer to rename "candidates" to "new_candidate_list".

[Andre, 2015/09/08 17:30:03]

Done.

+  OverlayCandidateList candidates = *candidate_list;
   candidates.push_back(candidate);
   candidates.back().plane_z_order = -1;
 
   // Check for support.
   capability_checker->CheckOverlaySupport(&candidates);
 
   // If the candidate can be handled by an overlay, create a pass for it. We
   // need to switch out the video quad with a black transparent one.
-  if (candidates[1].overlay_handled) {
+  if (candidates.back().overlay_handled) {
     const SharedQuadState* shared_quad_state =
-        candidate_iterator->shared_quad_state;
-    gfx::Rect rect = candidate_iterator->visible_rect;
+        (*candidate_iterator)->shared_quad_state;
+    gfx::Rect rect = (*candidate_iterator)->visible_rect;
     SolidColorDrawQuad* replacement =
         quad_list.ReplaceExistingElement<SolidColorDrawQuad>(
-            candidate_iterator);
+            *candidate_iterator);
     replacement->SetAll(shared_quad_state, rect, rect, rect, false,
                         SK_ColorTRANSPARENT, true);
     candidate_list->swap(candidates);
-    return true;
+    return CREATED_OVERLAY_STOP_LOOKING;
   }
-  return false;
+
+  return DID_NOT_CREATE_OVERLAY;
 }
 
 }  // namespace cc