Mac Overlays: Add sandwich strategy

cc/output/overlay_processor.cc

Index: cc/output/overlay_processor.cc
diff --git a/cc/output/overlay_processor.cc b/cc/output/overlay_processor.cc
index baae69dd10ed2bbe04e9178b1948c743a3356d23..463216b3947cfcba3e4bca64d7d89ab6f062c7f6 100644
--- a/cc/output/overlay_processor.cc
+++ b/cc/output/overlay_processor.cc
@@ -5,6 +5,7 @@
 #include "cc/output/overlay_processor.h"
 
 #include "cc/output/output_surface.h"
+#include "cc/output/overlay_strategy_sandwich.h"
 #include "cc/output/overlay_strategy_single_on_top.h"
 #include "cc/output/overlay_strategy_underlay.h"
 #include "ui/gfx/geometry/rect_conversions.h"
@@ -12,6 +13,9 @@
 
 namespace cc {
 
+OverlayProcessor::RendererState::RendererState() : device_scale_factor(1) {}
+OverlayProcessor::RendererState::~RendererState() {}
+
 OverlayProcessor::OverlayProcessor(OutputSurface* surface) : surface_(surface) {
 }
 
@@ -21,22 +25,30 @@ void OverlayProcessor::Initialize() {
   OverlayCandidateValidator* candidates =
       surface_->GetOverlayCandidateValidator();
   if (candidates) {
+#if defined(OS_MACOSX)

[ccameron, 2015/08/23 21:29:05]

Is this (the #ifdef) a reasonable way to go about this? Or would you prefer
something more dynamic.

I will not want to use the other strategies on Mac (Sandwich handles both).

[alexst (slow to review), 2015/08/24 15:07:02]

I hope to keep this platform agnostic. Maybe we could ask the output surface for
it's strategy list if possible? That way things will be hidden in the code
that's already OSX specific.

+    strategies_.push_back(
+        scoped_ptr<Strategy>(new OverlayStrategySandwich(candidates)));
+#else
     strategies_.push_back(
         scoped_ptr<Strategy>(new OverlayStrategySingleOnTop(candidates)));
     strategies_.push_back(
         scoped_ptr<Strategy>(new OverlayStrategyUnderlay(candidates)));
+#endif
   }
 }
 
 OverlayProcessor::~OverlayProcessor() {}
 
 void OverlayProcessor::ProcessForOverlays(
+    const OverlayProcessor::RendererState& renderer_state,
     RenderPassList* render_passes_in_draw_order,
     OverlayCandidateList* candidate_list) {
   for (StrategyList::iterator it = strategies_.begin(); it != strategies_.end();
        ++it) {
-    if ((*it)->Attempt(render_passes_in_draw_order, candidate_list))
+    if ((*it)->Attempt(renderer_state, render_passes_in_draw_order,
+                       candidate_list)) {
       return;
+    }
   }
 }