Split picture layer quads to allow removing more occluded area.

cc/layers/picture_layer_impl.cc

Index: cc/layers/picture_layer_impl.cc
diff --git a/cc/layers/picture_layer_impl.cc b/cc/layers/picture_layer_impl.cc
index f7d061fb701745dd1aa39546375fb59a66ed33bd..f9a13bf12174d9a90ecb2d01732e9fe4ecedd957 100644
--- a/cc/layers/picture_layer_impl.cc
+++ b/cc/layers/picture_layer_impl.cc
@@ -362,14 +362,18 @@ void PictureLayerImpl::AppendQuads(RenderPass* render_pass,
               geometry_rect.Intersects(scaled_viewport_for_tile_priority)) {
             append_quads_data->num_incomplete_tiles++;
           }
-
-          TileDrawQuad* quad =
-              render_pass->CreateAndAppendDrawQuad<TileDrawQuad>();
-          quad->SetNew(shared_quad_state, geometry_rect, opaque_rect,
-                       visible_geometry_rect, draw_info.resource_id(),
-                       texture_rect, draw_info.resource_size(),
-                       draw_info.contents_swizzled(), nearest_neighbor_);
-          ValidateQuadResources(quad);
+          Region unoccluded_region(visible_geometry_rect);
+          scaled_occlusion.OccludeContentRegion(&unoccluded_region);
+          for (Region::Iterator iterator(unoccluded_region);
+               iterator.has_rect(); iterator.next()) {
+            TileDrawQuad* quad =
+                render_pass->CreateAndAppendDrawQuad<TileDrawQuad>();
+            quad->SetNew(shared_quad_state, geometry_rect, opaque_rect,
+                         iterator.rect(), draw_info.resource_id(), texture_rect,
+                         draw_info.resource_size(),
+                         draw_info.contents_swizzled(), nearest_neighbor_);
+            ValidateQuadResources(quad);
+          }
           has_draw_quad = true;
           break;
         }
@@ -379,11 +383,16 @@ void PictureLayerImpl::AppendQuads(RenderPass* render_pass,
               shared_quad_state->opacity;
           if (mask_type_ == Layer::LayerMaskType::MULTI_TEXTURE_MASK ||
               alpha >= std::numeric_limits<float>::epsilon()) {
-            SolidColorDrawQuad* quad =
-                render_pass->CreateAndAppendDrawQuad<SolidColorDrawQuad>();
-            quad->SetNew(shared_quad_state, geometry_rect,
-                         visible_geometry_rect, draw_info.solid_color(), false);
-            ValidateQuadResources(quad);
+            Region unoccluded_region(visible_geometry_rect);
+            scaled_occlusion.OccludeContentRegion(&unoccluded_region);
+            for (Region::Iterator iterator(unoccluded_region);
+                 iterator.has_rect(); iterator.next()) {
+              SolidColorDrawQuad* quad =
+                  render_pass->CreateAndAppendDrawQuad<SolidColorDrawQuad>();
+              quad->SetNew(shared_quad_state, geometry_rect, iterator.rect(),
+                           draw_info.solid_color(), false);
+              ValidateQuadResources(quad);
+            }
           }
           has_draw_quad = true;
           break;