Adds stretch_to_fit support for surface aggregation.

This CL makes it so that if |stretch_to_fit_bounds| is set on a surface,
damage calculation takes this into account and scales the damage quad
accordingly.

Bug: 799512
Cq-Include-Trybots: master.tryserver.chromium.android:android_optional_gpu_tests_rel
Change-Id: I405ae815046d7ab51179bfceb0e54db9e5749725
Reviewed-on: https://chromium-review.googlesource.com/887789
Commit-Queue: CJ DiMeglio <lethalantidote@chromium.org>
Reviewed-by: enne <enne@chromium.org>
Cr-Commit-Position: refs/heads/master@{#533915}

components/viz/service/display/surface_aggregator.cc

@@ -880,13 +880,15 @@ gfx::Rect SurfaceAggregator::PrewalkTree(Surface* surface,
                 bool has_moved_pixels,
                 RenderPassId parent_pass_id,
                 const gfx::Transform& target_to_surface_transform,
-                const gfx::Rect& quad_rect)
+                const gfx::Rect& quad_rect,
+                bool stretch_content_to_fill_bounds)
         : primary_id(primary_id),
           fallback_id(fallback_id),
           has_moved_pixels(has_moved_pixels),
           parent_pass_id(parent_pass_id),
           target_to_surface_transform(target_to_surface_transform),
-          quad_rect(quad_rect) {}
+          quad_rect(quad_rect),
+          stretch_content_to_fill_bounds(stretch_content_to_fill_bounds) {}
 
     SurfaceId primary_id;
     base::Optional<SurfaceId> fallback_id;
@@ -894,6 +896,7 @@ gfx::Rect SurfaceAggregator::PrewalkTree(Surface* surface,
     RenderPassId parent_pass_id;
     gfx::Transform target_to_surface_transform;
     gfx::Rect quad_rect;
+    bool stretch_content_to_fill_bounds;
   };
   std::vector<SurfaceInfo> child_surfaces;
 
@@ -935,7 +938,7 @@ gfx::Rect SurfaceAggregator::PrewalkTree(Surface* surface,
         child_surfaces.emplace_back(
             surface_quad->primary_surface_id, surface_quad->fallback_surface_id,
             in_moved_pixel_pass, remapped_pass_id, target_to_surface_transform,
-            surface_quad->rect);
+            surface_quad->rect, surface_quad->stretch_content_to_fill_bounds);
       } else if (quad->material == DrawQuad::RENDER_PASS) {
         const auto* render_pass_quad = RenderPassDrawQuad::MaterialCast(quad);
         if (in_moved_pixel_pass) {
@@ -1002,9 +1005,26 @@ gfx::Rect SurfaceAggregator::PrewalkTree(Surface* surface,
     }
 
     if (child_surface) {
-      surface_damage.Union(
-          PrewalkTree(child_surface, surface_info.has_moved_pixels,
-                      surface_info.parent_pass_id, will_draw, result));
+      if (surface_info.stretch_content_to_fill_bounds) {
+        // Scale up the damage_quad generated by the child_surface to fit
+        // the containing quad_rect.
+        gfx::Rect child_rect =
+            PrewalkTree(child_surface, surface_info.has_moved_pixels,
+                        surface_info.parent_pass_id, will_draw, result);
+        if (child_surface->size_in_pixels().GetCheckedArea().ValueOrDefault(0) >
+            0) {
+          float y_scale = static_cast<float>(surface_info.quad_rect.height()) /
+                          child_surface->size_in_pixels().height();
+          float x_scale = static_cast<float>(surface_info.quad_rect.width()) /
+                          child_surface->size_in_pixels().width();
+          surface_damage.Union(
+              gfx::ScaleToEnclosingRect(child_rect, x_scale, y_scale));
+        }
+      } else {
+        surface_damage.Union(
+            PrewalkTree(child_surface, surface_info.has_moved_pixels,
+                        surface_info.parent_pass_id, will_draw, result));
+      }
     }
 
     if (surface_damage.IsEmpty())