cc: Move animate steps from proxies to LayerTreeHostImpl.

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 <algorithm>
 #include <limits>
 #include <map>
 #include <set>
@@ skipping 403 matching lines @@
   }
   if (EvictedUIResourcesExist()) {
     TRACE_EVENT_INSTANT0(
         "cc", "LayerTreeHostImpl::CanDraw UI resources evicted not recreated",
         TRACE_EVENT_SCOPE_THREAD);
     return false;
   }
   return true;
 }
 
-void LayerTreeHostImpl::Animate(base::TimeTicks monotonic_time) {
+void LayerTreeHostImpl::Animate() {
+  // Don't animate if there is no active root layer.
+  // TODO(ajuma): Does this break things if first commit has an animation?

[ajuma, 2015/08/19 21:05:02]

I suspect it will if break things if we move post-commit animation to happen
right after commit rather than right before we draw. I think the right fix (in a
later CL) is to remove this early-out.

+  if (!active_tree()->root_layer())
+    return;
+
+  base::TimeTicks monotonic_time = CurrentBeginFrameArgs().frame_time;
+
   // mithro(TODO): Enable these checks.
   // DCHECK(!current_begin_frame_tracker_.HasFinished());
   // DCHECK(monotonic_time == current_begin_frame_tracker_.Current().frame_time)
   //  << "Called animate with unknown frame time!?";
   if (!root_layer_scroll_offset_delegate_ ||
       (CurrentlyScrollingLayer() != InnerViewportScrollLayer() &&
-       CurrentlyScrollingLayer() != OuterViewportScrollLayer())) {
+       CurrentlyScrollingLayer() != OuterViewportScrollLayer()))
     AnimateInput(monotonic_time);
-  }
   AnimatePageScale(monotonic_time);
   AnimateLayers(monotonic_time);
   AnimateScrollbars(monotonic_time);
   AnimateTopControls(monotonic_time);
+
+  // If animations are not visible, update the state now as Draw/Swap will never
+  // occur.
+  // TODO(ajuma): Left-overs from now-deleted background ticking?

[ajuma, 2015/08/19 21:05:02]

Sure looks like it.

+  bool animations_are_visible = visible() && CanDraw();
+  if (!animations_are_visible)
+    UpdateAnimationState(true);
 }
 
 bool LayerTreeHostImpl::PrepareTiles() {
   if (!tile_priorities_dirty_)
     return false;
 
   client_->WillPrepareTiles();
   bool did_prepare_tiles = tile_manager_->PrepareTiles(global_tile_state_);
   if (did_prepare_tiles)
     tile_priorities_dirty_ = false;
@@ skipping 3194 matching lines @@
   if (active_tree()) {
     LayerAnimationValueProvider* layer = active_tree()->LayerById(layer_id);
     if (layer)
       return layer->ScrollOffsetForAnimation();
   }
 
   return gfx::ScrollOffset();
 }
 
 }  // namespace cc