Fix mac memory regression for https://crrev.com/c/2030627

Mac promotes all render passes to CALayer, so we don't need to redraw
the main surface.

Bug: 1048997,1044678
Change-Id: Iefef04a00ff60df882877b5930c90bcc8057e485
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2039335
Commit-Queue: Peng Huang <penghuang@chromium.org>
Reviewed-by: kylechar <kylechar@chromium.org>
Cr-Commit-Position: refs/heads/master@{#739285}

components/viz/service/display/direct_renderer.cc

@@ -381,8 +381,16 @@ void DirectRenderer::DrawFrame(RenderPassList* render_passes_in_draw_order,
                                                 : gfx::BufferFormat::RGBX_8888,
 
                              reshape_use_stencil_);
+#if defined(OS_MACOSX)
+    // For Mac, all render passes will be promoted to CALayer, the redraw full
+    // frame is for the main surface only.
+    // TODO(penghuang): verify this logic with SkiaRenderer.
+    if (!output_surface_->capabilities().supports_surfaceless)
+      needs_full_frame_redraw = true;
+#else
     // The entire surface has to be redrawn if reshape is requested.
     needs_full_frame_redraw = true;
+#endif
   }
 
 #if defined(OS_WIN)