DirectRenderer allows empty swap rects for CommitOverlayPlanes

cc/output/gl_renderer.cc

 // Copyright 2010 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "cc/output/gl_renderer.h"
 
 #include <algorithm>
 #include <limits>
 #include <set>
 #include <string>
@@ skipping 330 matching lines @@
       on_demand_tile_raster_resource_id_(0),
       bound_geometry_(NO_BINDING) {
   DCHECK(gl_);
   DCHECK(context_support_);
 
   ContextProvider::Capabilities context_caps =
       output_surface_->context_provider()->ContextCapabilities();
 
   capabilities_.using_partial_swap =
       settings_->partial_swap_enabled && context_caps.gpu.post_sub_buffer;
+  capabilities_.allow_empty_swap = capabilities_.using_partial_swap ||
+                                   context_caps.gpu.commit_overlay_planes;
 
   DCHECK(!context_caps.gpu.iosurface || context_caps.gpu.texture_rectangle);
 
   capabilities_.using_egl_image = context_caps.gpu.egl_image_external;
 
   capabilities_.max_texture_size = resource_provider_->max_texture_size();
   capabilities_.best_texture_format = resource_provider_->best_texture_format();
 
   // The updater can access textures while the GLRenderer is using them.
   capabilities_.allow_partial_texture_updates = true;
@@ skipping 2250 matching lines @@
     // If supported, we can save significant bandwidth by only swapping the
     // damaged/scissored region (clamped to the viewport).
     swap_buffer_rect_.Intersect(gfx::Rect(surface_size));
     int flipped_y_pos_of_rect_bottom = surface_size.height() -
                                        swap_buffer_rect_.y() -
                                        swap_buffer_rect_.height();
     compositor_frame.gl_frame_data->sub_buffer_rect =
         gfx::Rect(swap_buffer_rect_.x(),
                   FlippedRootFramebuffer() ? flipped_y_pos_of_rect_bottom
                                            : swap_buffer_rect_.y(),
-                  swap_buffer_rect_.width(),
-                  swap_buffer_rect_.height());
+                  swap_buffer_rect_.width(), swap_buffer_rect_.height());
   } else {
-    compositor_frame.gl_frame_data->sub_buffer_rect =
-        gfx::Rect(output_surface_->SurfaceSize());
+    // Expand the swap rect to the full surface unless it's empty, and empty
+    // swap is allowed.
+    if (!swap_buffer_rect_.IsEmpty() || !capabilities_.allow_empty_swap) {
+      swap_buffer_rect_ = gfx::Rect(surface_size);
+    }
+    compositor_frame.gl_frame_data->sub_buffer_rect = swap_buffer_rect_;
   }
   output_surface_->SwapBuffers(&compositor_frame);
 
   // We always hold onto resources for an extra frame, to make sure we don't
   // update the buffer while it's being scanned out. On some platforms, hold
   // on to resources for an extra frame.
   if (settings_->delay_releasing_overlay_resources) {
     previous_swap_overlay_resources_[1].clear();
     previous_swap_overlay_resources_[1].swap(
         previous_swap_overlay_resources_[0]);
@@ skipping 941 matching lines @@
       texture_id = pending_overlay_resources_.back()->texture_id();
     }
 
     context_support_->ScheduleOverlayPlane(
         overlay.plane_z_order, overlay.transform, texture_id,
         ToNearestRect(overlay.display_rect), overlay.uv_rect);
   }
 }
 
 }  // namespace cc