mac: Fix IOSurface clearing for RPDQ CALayer promotion.

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 3957 matching lines @@
 
   gl_->GenFramebuffers(1, &temp_fbo);
   gl_->BindFramebuffer(GL_FRAMEBUFFER, temp_fbo);
   gl_->FramebufferTexture2D(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0,
                             destination.target(), destination.texture_id(), 0);
   DCHECK(gl_->CheckFramebufferStatus(GL_FRAMEBUFFER) ==
          GL_FRAMEBUFFER_COMPLETE);
 
   // Clear to 0 to ensure the background is transparent.
   gl_->ClearColor(0, 0, 0, 0);
+  if (is_scissor_enabled_)
+    gl_->Disable(GL_SCISSOR_TEST);
   gl_->Clear(GL_COLOR_BUFFER_BIT);
+  if (is_scissor_enabled_)
+    gl_->Enable(GL_SCISSOR_TEST);
 
   UpdateRPDQTexturesForSampling(&params);
   UpdateRPDQBlendMode(&params);
   ChooseRPDQProgram(&params);
   UpdateRPDQUniforms(&params);
 
   // Prior to drawing, set up the destination framebuffer and viewport.
   gl_->BindFramebuffer(GL_FRAMEBUFFER, temp_fbo);
   gl_->Viewport(0, 0, updated_dst_rect.width(), updated_dst_rect.height());
 
@@ skipping 49 matching lines @@
 
   gl_->ScheduleCALayerSharedStateCHROMIUM(
       ca_layer_overlay->shared_state->opacity, is_clipped, clip_rect,
       sorting_context_id, gl_transform);
   gl_->ScheduleCALayerCHROMIUM(
       texture_id, contents_rect, ca_layer_overlay->background_color,
       ca_layer_overlay->edge_aa_mask, bounds_rect, filter);
 }
 
 }  // namespace cc