cc: Make OutputSurfaceFrame::sub_buffer_rect optional

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 <stddef.h>
 #include <stdint.h>
 
 #include <algorithm>
@@ skipping 2630 matching lines @@
     // 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();
     output_frame.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());
   } else {

[danakj, 2017/02/22 00:36:57]

else if

[halliwell, 2017/02/22 14:19:27]

Done.

     // Expand the swap rect to the full surface unless it's empty, and empty
     // swap is allowed.
-    if (!swap_buffer_rect_.IsEmpty() || !allow_empty_swap_) {
+    if (swap_buffer_rect_.IsEmpty() && allow_empty_swap_) {
+      output_frame.sub_buffer_rect = swap_buffer_rect_;
+    } else {

[danakj, 2017/02/22 00:36:57]

i dont think we need this else, we clear the rect at the bottom of the method

[halliwell, 2017/02/22 14:19:27]

Done.

       swap_buffer_rect_ = gfx::Rect(surface_size);
     }
-    output_frame.sub_buffer_rect = swap_buffer_rect_;
   }
 
   swapping_overlay_resources_.push_back(std::move(pending_overlay_resources_));
   pending_overlay_resources_.clear();
 
   output_surface_->SwapBuffers(std::move(output_frame));
 
   swap_buffer_rect_ = gfx::Rect();
 }
 
@@ skipping 862 matching lines @@
     return;
 
   // Report GPU overdraw as a percentage of |max_result|.
   TRACE_COUNTER1(
       TRACE_DISABLED_BY_DEFAULT("cc.debug.overdraw"), "GPU Overdraw",
       (std::accumulate(overdraw->begin(), overdraw->end(), 0) * 100) /
           max_result);
 }
 
 }  // namespace cc