Mac Overlays: Add AllOrNothing strategy

cc/output/overlay_strategy_all_or_nothing.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_all_or_nothing.h"
+
+#include "cc/output/overlay_candidate_validator.h"
+#include "cc/quads/draw_quad.h"
+
+namespace cc {
+
+OverlayStrategyAllOrNothing::OverlayStrategyAllOrNothing(
+    OverlayCandidateValidator* capability_checker)
+    : capability_checker_(capability_checker) {}
+
+OverlayStrategyAllOrNothing::~OverlayStrategyAllOrNothing() {}
+
+bool OverlayStrategyAllOrNothing::Attempt(
+    RenderPassList* render_passes_in_draw_order,
+    OverlayCandidateList* candidates,
+    float device_scale_factor) {
+  QuadList& quad_list = render_passes_in_draw_order->back()->quad_list;
+  OverlayCandidateList new_candidates;
+
+  for (const DrawQuad* quad : quad_list) {
+    OverlayCandidate candidate;
+    if (!OverlayCandidate::FromDrawQuad(quad, &candidate))
+      return false;
+    new_candidates.push_back(candidate);
+  }
+
+  int next_z_order = 1;
+  for (auto it = new_candidates.rbegin(); it != new_candidates.rend(); ++it)
+    it->plane_z_order = next_z_order++;

[ccameron, 2015/09/29 23:29:56]

This can be rolled into the above loop by just having the z orders be -1, -2,
-3, (we will not schedule plane for z=0 in this strategy).

[Andre, 2015/09/30 00:18:38]

Done.

+
+  capability_checker_->CheckOverlaySupport(&new_candidates);
+  for (const OverlayCandidate& candidate : new_candidates) {
+    if (candidate.plane_z_order > 0 && !candidate.overlay_handled)
+      return false;
+  }
+
+  quad_list.clear();
+  candidates->swap(new_candidates);
+  return true;
+}
+
+}  // namespace cc