Support optimized root damage rect for multiple overlays on Windows

If the overlays are the only damages in the frame, we will get a zero
root damage rect with the new way of calculating damage rect
|use_overlay_damage_list_|, which is enabled by default.

The old code of |use_overlay_damage_list_| == false is still working. It
will be cleaned up once the new code is stable.

Bug:1117235

Change-Id: Ibbede44056973a5ba9e052292673bbf0bcb4a50a
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2434905
Commit-Queue: Maggie Chen <magchen@chromium.org>
Reviewed-by: Sunny Sachanandani <sunnyps@chromium.org>
Reviewed-by: weiliangc <weiliangc@chromium.org>
Cr-Commit-Position: refs/heads/master@{#818723}

components/viz/service/display/dc_layer_overlay.h

@@ -140,10 +140,20 @@ class VIZ_SERVICE_EXPORT DCLayerOverlayProcessor
                           gfx::Rect* this_frame_underlay_rect,
                           DCLayerOverlay* dc_layer);
 
+  void UpdateRootDamageRect(const gfx::RectF& display_rect,
+                            gfx::Rect* damage_rect);
+
+  void RemoveOverlayDamageRect(const QuadList::Iterator& it,
+                               const gfx::Rect& quad_rectangle,
+                               const gfx::Rect& occluding_damage_rect,
+                               gfx::Rect* damage_rect);
+
   void InsertDebugBorderDrawQuad(const DCLayerOverlayList* dc_layer_overlays,
                                  AggregatedRenderPass* render_pass,
                                  const gfx::RectF& display_rect,
                                  gfx::Rect* damage_rect);
+  bool IsPreviousFrameUnderlayRect(const gfx::Rect& quad_rectangle,
+                                   size_t index);
 
   bool has_overlay_support_;
   const bool use_overlay_damage_list_;
@@ -162,6 +172,18 @@ class VIZ_SERVICE_EXPORT DCLayerOverlayProcessor
   int previous_frame_processed_overlay_count_ = 0;
   int current_frame_processed_overlay_count_ = 0;
 
+  struct OverlayRect {
+    gfx::Rect rect;
+    bool is_overlay;  // If false, it's an underlay.
+    bool operator==(const OverlayRect& b) {
+      return rect == b.rect && is_overlay == b.is_overlay;
+    }
+    bool operator!=(const OverlayRect& b) { return !(*this == b); }
+  };
+  std::vector<OverlayRect> previous_frame_overlay_rects_;
+  std::vector<OverlayRect> current_frame_overlay_rects_;
+  SurfaceDamageRectList* surface_damage_rect_list_;
+
   scoped_refptr<base::SingleThreadTaskRunner> viz_task_runner_;
 
   DISALLOW_COPY_AND_ASSIGN(DCLayerOverlayProcessor);

components/viz/service/display/display.cc

@@ -720,6 +720,7 @@ bool Display::DrawAndSwap(base::TimeTicks expected_display_time) {
     // skip the draw and so that the GL swap won't stretch the output.
     last_render_pass.output_rect.set_size(current_surface_size);
     last_render_pass.damage_rect = last_render_pass.output_rect;
+    frame.surface_damage_rect_list_.push_back(last_render_pass.damage_rect);
   }
   surface_size = last_render_pass.output_rect.size();
   have_damage = !last_render_pass.damage_rect.size().IsEmpty();

components/viz/service/display/overlay_processor_win.h

@@ -74,6 +74,7 @@ class VIZ_SERVICE_EXPORT OverlayProcessorWin
   bool using_dc_layers_ = false;
   // Number of frames since the last time direct composition layers were used.
   int frames_since_using_dc_layers_ = 0;
+
   // TODO(weiliangc): Eventually fold DCLayerOverlayProcessor into this class.
   std::unique_ptr<DCLayerOverlayProcessor> dc_layer_overlay_processor_;