Reland: Correctly handle damage involving filters in SurfaceAggregator

cc/output/direct_renderer.cc

Index: cc/output/direct_renderer.cc
diff --git a/cc/output/direct_renderer.cc b/cc/output/direct_renderer.cc
index 8bb36e5288b838b44256d5e902474520d4d1b88f..aaf1fcca4f7833624a97009dabfb147af58e83ac 100644
--- a/cc/output/direct_renderer.cc
+++ b/cc/output/direct_renderer.cc
@@ -278,23 +278,18 @@ void DirectRenderer::DrawFrame(RenderPassList* render_passes_in_draw_order,
 
 gfx::Rect DirectRenderer::ComputeScissorRectForRenderPass(
     const DrawingFrame* frame) {
-  gfx::Rect render_pass_scissor = frame->current_render_pass->output_rect;
-
-  if (frame->root_damage_rect == frame->root_render_pass->output_rect ||
-      !frame->current_render_pass->copy_requests.empty())
-    return render_pass_scissor;
-
-  gfx::Transform inverse_transform(gfx::Transform::kSkipInitialization);
-  if (frame->current_render_pass->transform_to_root_target.GetInverse(
-          &inverse_transform)) {
-    // Only intersect inverse-projected damage if the transform is invertible.
-    gfx::Rect damage_rect_in_render_pass_space =
-        MathUtil::ProjectEnclosingClippedRect(inverse_transform,
-                                              frame->root_damage_rect);
-    render_pass_scissor.Intersect(damage_rect_in_render_pass_space);
-  }
+  if (frame->current_render_pass == frame->root_render_pass)
+    return frame->root_damage_rect;
+
+  // If the root damage rect has been expanded due to overlays, all the other
+  // damage rect calculations are incorrect.
+  if (!frame->root_render_pass->damage_rect.Contains(frame->root_damage_rect))
+    return frame->current_render_pass->output_rect;
 
-  return render_pass_scissor;
+  DCHECK(frame->current_render_pass->copy_requests.empty() ||
+         (frame->current_render_pass->damage_rect ==
+          frame->current_render_pass->output_rect));
+  return frame->current_render_pass->damage_rect;
 }
 
 bool DirectRenderer::NeedDeviceClip(const DrawingFrame* frame) const {