cc: Plumb device color space through to rasterization

cc/trees/layer_tree_host_impl.cc

 // Copyright 2011 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/trees/layer_tree_host_impl.h"
 
 #include <stddef.h>
 #include <stdint.h>
 
 #include <algorithm>
@@ skipping 1305 matching lines @@
 
 void LayerTreeHostImpl::SetIsLikelyToRequireADraw(
     bool is_likely_to_require_a_draw) {
   // Proactively tell the scheduler that we expect to draw within each vsync
   // until we get all the tiles ready to draw. If we happen to miss a required
   // for draw tile here, then we will miss telling the scheduler each frame that
   // we intend to draw so it may make worse scheduling decisions.
   is_likely_to_require_a_draw_ = is_likely_to_require_a_draw;
 }
 
+const gfx::ColorSpace& LayerTreeHostImpl::GetTileColorSpace() const {
+  return sync_tree()->device_color_space();

[ccameron, 2016/09/13 23:34:16]

I'd vaguely want to put the device_color_space hanging off of the
LayerTreeHostImpl instead of the LayerTreeHost, but there seemed to be little
precedent for doing such a thing. Does pulling it from the sync_tree seem
reasonable here?

[vmpstr, 2016/09/14 23:00:43]

sync_tree might be nullptr, right? If we activate and scroll on the compositor
thread, then new tiles would have to access this

[ccameron, 2016/09/15 07:13:42]

I was planning to have this return a gfx::ColorSpace (instead of the const
reference) and just return the default value if there were no tree (sync_tree is
"pending_tree ? pending_tree : active_tree"), but then I found that that case
wasn't hit (at least in unittests and basic browsing).

That said, now that we've lifted the call to this out of the main loop, we might
as well have it return by value.

+}
+
 void LayerTreeHostImpl::NotifyReadyToActivate() {
   client_->NotifyReadyToActivate();
 }
 
 void LayerTreeHostImpl::NotifyReadyToDraw() {
   // Tiles that are ready will cause NotifyTileStateChanged() to be called so we
   // don't need to schedule a draw here. Just stop WillBeginImplFrame() from
   // causing optimistic requests to draw a frame.
   is_likely_to_require_a_draw_ = false;
 
@@ skipping 2843 matching lines @@
   if (is_visible) {
     worker_context_visibility_ =
         worker_context->CacheController()->ClientBecameVisible();
   } else {
     worker_context->CacheController()->ClientBecameNotVisible(
         std::move(worker_context_visibility_));
   }
 }
 
 }  // namespace cc