Split DCLayerOverlayProcessor::Process into three functions.

cc/output/dc_layer_overlay.cc

Index: cc/output/dc_layer_overlay.cc
diff --git a/cc/output/dc_layer_overlay.cc b/cc/output/dc_layer_overlay.cc
index e5a043dd218b7d2281386ca54adf6e8a6b54ecc8..28b68a39f0a3cf8184c35c0337ec38d1c4b95991 100644
--- a/cc/output/dc_layer_overlay.cc
+++ b/cc/output/dc_layer_overlay.cc
@@ -129,11 +129,10 @@ void DCLayerOverlayProcessor::Process(ResourceProvider* resource_provider,
                                       gfx::Rect* damage_rect,
                                       DCLayerOverlayList* ca_layer_overlays) {
   gfx::Rect this_frame_underlay_rect;
-  bool display_rect_changed = (display_rect != previous_display_rect_);
   for (auto it = quad_list->begin(); it != quad_list->end(); ++it) {
-    DCLayerOverlay ca_layer;
+    DCLayerOverlay dc_layer;
     DCLayerResult result = FromDrawQuad(resource_provider, display_rect,
-                                        quad_list->begin(), it, &ca_layer);
+                                        quad_list->begin(), it, &dc_layer);
     if (result != DC_LAYER_SUCCESS) {
       RecordDCLayerResult(result);
       continue;
@@ -150,69 +149,100 @@ void DCLayerOverlayProcessor::Process(ResourceProvider* resource_provider,
     gfx::Rect quad_rectangle = gfx::ToEnclosingRect(ClippedQuadRectangle(*it));
     gfx::RectF occlusion_bounding_box =
         GetOcclusionBounds(gfx::RectF(quad_rectangle), quad_list->begin(), it);
-    if (occlusion_bounding_box.IsEmpty()) {
-      // The quad is on top, so promote it to an overlay and remove all damage
-      // underneath it.
-      if (it->shared_quad_state->quad_to_target_transform
-              .Preserves2dAxisAlignment() &&
-          !display_rect_changed && !it->ShouldDrawWithBlending()) {
-        damage_rect->Subtract(quad_rectangle);
-      }
-      quad_list->EraseAndInvalidateAllPointers(it);
-    } else if (!base::FeatureList::IsEnabled(
-                   features::kDirectCompositionUnderlays)) {
-      RecordDCLayerResult(DC_LAYER_FAILED_OCCLUDED);
-      continue;
-    } else {
-      // The quad is occluded, so replace it with a black solid color quad and
-      // place the overlay itself under the quad.
-      if (it->shared_quad_state->quad_to_target_transform
-              .IsIdentityOrIntegerTranslation()) {
-        this_frame_underlay_rect = quad_rectangle;
-      }
-      ca_layer.shared_state->z_order = -1;
-      const SharedQuadState* shared_quad_state = it->shared_quad_state;
-      gfx::Rect rect = it->visible_rect;
-      SolidColorDrawQuad* replacement =
-          quad_list->ReplaceExistingElement<SolidColorDrawQuad>(it);
-      replacement->SetAll(shared_quad_state, rect, rect, rect, false,
-                          SK_ColorTRANSPARENT, true);
-
-      if (this_frame_underlay_rect == previous_frame_underlay_rect_) {
-        // If this underlay rect is the same as for last frame, subtract its
-        // area from the damage of the main surface, as the cleared area was
-        // already cleared last frame. Add back the damage from the occluded
-        // area for this and last frame, as that may have changed.
-        if (it->shared_quad_state->quad_to_target_transform
-                .Preserves2dAxisAlignment() &&
-            !display_rect_changed) {
-          gfx::Rect occluding_damage_rect = *damage_rect;
-          occluding_damage_rect.Intersect(quad_rectangle);
-          damage_rect->Subtract(quad_rectangle);
-          gfx::Rect new_occlusion_bounding_box =
-              gfx::ToEnclosingRect(occlusion_bounding_box);
-          new_occlusion_bounding_box.Union(previous_occlusion_bounding_box_);
-          occluding_damage_rect.Intersect(new_occlusion_bounding_box);
-
-          damage_rect->Union(occluding_damage_rect);
-        }
-      } else {
-        // Entire replacement quad must be redrawn.
-        damage_rect->Union(quad_rectangle);
-      }
-      previous_occlusion_bounding_box_ =
-          gfx::ToEnclosingRect(occlusion_bounding_box);
-    }
-    overlay_damage_rect->Union(quad_rectangle);
 
-    RecordDCLayerResult(DC_LAYER_SUCCESS);
-    ca_layer_overlays->push_back(ca_layer);
-    // Only allow one overlay for now.
-    break;
+    // Underlays are less efficient, so attempt regular overlays first.
+    if (ProcessForOverlay(display_rect, quad_list, quad_rectangle,
+                          occlusion_bounding_box, it, damage_rect) ||
+        ProcessForUnderlay(display_rect, quad_list, quad_rectangle,
+                           occlusion_bounding_box, it, damage_rect,
+                           &this_frame_underlay_rect, &dc_layer)) {
+      overlay_damage_rect->Union(quad_rectangle);
+
+      RecordDCLayerResult(DC_LAYER_SUCCESS);
+      ca_layer_overlays->push_back(dc_layer);
+      // Only allow one overlay for now.
+      break;
+    }
   }
   damage_rect->Intersect(gfx::ToEnclosingRect(display_rect));
   previous_frame_underlay_rect_ = this_frame_underlay_rect;
   previous_display_rect_ = display_rect;
 }
 
+bool DCLayerOverlayProcessor::ProcessForOverlay(
+    const gfx::RectF& display_rect,
+    QuadList* quad_list,
+    const gfx::Rect& quad_rectangle,
+    const gfx::RectF& occlusion_bounding_box,
+    const QuadList::Iterator& it,
+    gfx::Rect* damage_rect) {
+  bool display_rect_changed = (display_rect != previous_display_rect_);
+  if (!occlusion_bounding_box.IsEmpty())
+    return false;
+  // The quad is on top, so promote it to an overlay and remove all damage
+  // underneath it.
+  if (it->shared_quad_state->quad_to_target_transform
+          .Preserves2dAxisAlignment() &&
+      !display_rect_changed && !it->ShouldDrawWithBlending()) {
+    damage_rect->Subtract(quad_rectangle);
+  }
+  quad_list->EraseAndInvalidateAllPointers(it);
+  return true;
+}
+
+bool DCLayerOverlayProcessor::ProcessForUnderlay(
+    const gfx::RectF& display_rect,
+    QuadList* quad_list,
+    const gfx::Rect& quad_rectangle,
+    const gfx::RectF& occlusion_bounding_box,
+    const QuadList::Iterator& it,
+    gfx::Rect* damage_rect,
+    gfx::Rect* this_frame_underlay_rect,
+    DCLayerOverlay* dc_layer) {
+  if (!base::FeatureList::IsEnabled(features::kDirectCompositionUnderlays)) {
+    RecordDCLayerResult(DC_LAYER_FAILED_OCCLUDED);
+    return false;
+  }
+  bool display_rect_changed = (display_rect != previous_display_rect_);
+  // The quad is occluded, so replace it with a black solid color quad and
+  // place the overlay itself under the quad.
+  if (it->shared_quad_state->quad_to_target_transform
+          .IsIdentityOrIntegerTranslation()) {
+    *this_frame_underlay_rect = quad_rectangle;
+  }
+  dc_layer->shared_state->z_order = -1;
+  const SharedQuadState* shared_quad_state = it->shared_quad_state;
+  gfx::Rect rect = it->visible_rect;
+  SolidColorDrawQuad* replacement =
+      quad_list->ReplaceExistingElement<SolidColorDrawQuad>(it);
+  replacement->SetAll(shared_quad_state, rect, rect, rect, false,
+                      SK_ColorTRANSPARENT, true);
+
+  if (*this_frame_underlay_rect == previous_frame_underlay_rect_) {
+    // If this underlay rect is the same as for last frame, subtract its
+    // area from the damage of the main surface, as the cleared area was
+    // already cleared last frame. Add back the damage from the occluded
+    // area for this and last frame, as that may have changed.
+    if (it->shared_quad_state->quad_to_target_transform
+            .Preserves2dAxisAlignment() &&
+        !display_rect_changed) {
+      gfx::Rect occluding_damage_rect = *damage_rect;
+      occluding_damage_rect.Intersect(quad_rectangle);
+      damage_rect->Subtract(quad_rectangle);
+      gfx::Rect new_occlusion_bounding_box =
+          gfx::ToEnclosingRect(occlusion_bounding_box);
+      new_occlusion_bounding_box.Union(previous_occlusion_bounding_box_);
+      occluding_damage_rect.Intersect(new_occlusion_bounding_box);
+
+      damage_rect->Union(occluding_damage_rect);
+    }
+  } else {
+    // Entire replacement quad must be redrawn.
+    damage_rect->Union(quad_rectangle);
+  }
+  previous_occlusion_bounding_box_ =
+      gfx::ToEnclosingRect(occlusion_bounding_box);
+  return true;
+}
+
 }  // namespace cc