Force use of and cache render surface.

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 b97dec844b74a91eda2f5a96c5dce6fe0e246cb0..c1683683e53e6e17fc84112d25f09826d0491564 100644
--- a/cc/output/direct_renderer.cc
+++ b/cc/output/direct_renderer.cc
@@ -627,6 +627,14 @@ bool DirectRenderer::UseRenderPass(const RenderPass* render_pass) {
   }
   DCHECK(texture->id());
 
+  if (render_pass->cache_render_surface &&
+      !render_pass->has_damage_from_contributing_content) {
+    return false;
+  }
+
+  if (current_frame()->ComputeScissorRectForRenderPass().IsEmpty())

[weiliangc, 2017/07/10 19:19:46]

Does this still hold when we are not using partial_swap?

[jbauman, 2017/07/11 02:09:44]

If the scissor rect is empty then nothing's being drawn to the texture, whether
or not partial swap is being used. Whether the scissor rect is empty depends,
for the root render pass, on whether partial swap is enabled.

+    return false;
+
   if (BindFramebufferToTexture(texture)) {
     InitializeViewport(current_frame(), render_pass->output_rect,
                        gfx::Rect(render_pass->output_rect.size()),