mac: Fix bug where opacity is applied twice on RenderPassDrawQuads.

cc/output/gl_renderer.cc

Index: cc/output/gl_renderer.cc
diff --git a/cc/output/gl_renderer.cc b/cc/output/gl_renderer.cc
index fe9c5d8160678b2bfb02fad747fb4d8dbe7c3b21..3f642d05eb79df68ba8235dea8c759b5e2b72749 100644
--- a/cc/output/gl_renderer.cc
+++ b/cc/output/gl_renderer.cc
@@ -4042,9 +4042,10 @@ void GLRenderer::ScheduleRenderPassDrawQuad(
   transform.asColMajorf(gl_transform);
   unsigned filter = ca_layer_overlay->filter;
 
-  gl_->ScheduleCALayerSharedStateCHROMIUM(
-      ca_layer_overlay->shared_state->opacity, is_clipped, clip_rect,
-      sorting_context_id, gl_transform);
+  // The alpha has already been applied when copying the RPDQ to an IOSurface.
+  GLfloat alpha = 1;
+  gl_->ScheduleCALayerSharedStateCHROMIUM(alpha, 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);