Mac Overlays: Allow multiple overlays with sandwich strategy

cc/output/overlay_strategy_common.cc

 // Copyright 2015 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_common.h"
 
 #include <limits>
 
 #include "cc/quads/io_surface_draw_quad.h"
 #include "cc/quads/solid_color_draw_quad.h"
@@ skipping 10 matching lines @@
     OverlayCandidateValidator* capability_checker,
     OverlayStrategyCommonDelegate* delegate)
     : capability_checker_(capability_checker), delegate_(delegate) {}
 
 OverlayStrategyCommon::~OverlayStrategyCommon() {
 }
 
 bool OverlayStrategyCommon::Attempt(RenderPassList* render_passes_in_draw_order,
                                     OverlayCandidateList* candidate_list,
                                     float device_scale_factor) {
+  DCHECK(candidate_list->empty());
   if (!capability_checker_)
     return false;
   RenderPass* root_render_pass = render_passes_in_draw_order->back();
   DCHECK(root_render_pass);
 
   QuadList& quad_list = root_render_pass->quad_list;
-  for (auto it = quad_list.begin(); it != quad_list.end(); ++it) {
+  auto it = quad_list.begin();
+  while (it != quad_list.end()) {
     OverlayCandidate candidate;
     const DrawQuad* draw_quad = *it;
     if (IsOverlayQuad(draw_quad) &&
-        GetCandidateQuadInfo(*draw_quad, &candidate) &&
-        delegate_->TryOverlay(capability_checker_, render_passes_in_draw_order,
-                              candidate_list, candidate, it,
-                              device_scale_factor))
-      return true;
+        GetCandidateQuadInfo(*draw_quad, &candidate)) {
+      it = delegate_->TryOverlay(capability_checker_,

[ccameron, 2015/09/02 21:41:55]

Then this just reads

  ...
  if (delegate_->TryOverlay(...) == STOP)) break;
  if (it == quad_list.end()) break;
  ++it;
}

[ccameron, 2015/09/02 22:22:33]

Errr...

  result = delegate_->TryOverlay(...)
  if (result == ...STOP) break
  if (result == DID_NOT_ADD) ++iter

[Andre, 2015/09/03 22:45:59]

Done.

+                                 render_passes_in_draw_order, candidate_list,
+                                 candidate, it, device_scale_factor);
+    } else {
+      ++it;
+    }
   }
-  return false;
+
+  return !candidate_list->empty();
 }
 
 bool OverlayStrategyCommon::IsOverlayQuad(const DrawQuad* draw_quad) {
   switch (draw_quad->material) {
     case DrawQuad::TEXTURE_CONTENT:
       return TextureDrawQuad::MaterialCast(draw_quad)->allow_overlay();
     case DrawQuad::STREAM_VIDEO_CONTENT:
       return StreamVideoDrawQuad::MaterialCast(draw_quad)->allow_overlay();
     case DrawQuad::IO_SURFACE_CONTENT:
       return IOSurfaceDrawQuad::MaterialCast(draw_quad)->allow_overlay;
@@ skipping 116 matching lines @@
       return false;
   }
 
   quad_info->format = RGBA_8888;
   quad_info->display_rect = OverlayCandidate::GetOverlayRect(
       draw_quad.shared_quad_state->quad_to_target_transform, draw_quad.rect);
   return true;
 }
 
 }  // namespace cc