cc: Always call PrepareTiles on visibility change.

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 1930 matching lines @@
   DidVisibilityChange(this, visible_);
   EnforceManagedMemoryPolicy(ActualManagedMemoryPolicy());
 
   // If we just became visible, we have to ensure that we draw high res tiles,
   // to prevent checkerboard/low res flashes.
   if (visible_)
     SetRequiresHighResToDraw();
   else
     EvictAllUIResources();
 
-  // Evict tiles immediately if invisible since this tab may never get another
-  // draw or timer tick.
-  if (!visible_)
-    PrepareTiles();
+  // Call PrepareTiles unconditionally on visibility change since this tab may
+  // never get another draw or timer tick. When becoming visible we care about
+  // unblocking the scheduler which might be waiting for activation / ready to
+  // draw. When becoming invisible we care about evicting tiles immediately.
+  PrepareTiles();
 
   if (!renderer_)
     return;
 
   renderer_->SetVisible(visible);
 }
 
 void LayerTreeHostImpl::SetNeedsAnimate() {
   NotifySwapPromiseMonitorsOfSetNeedsRedraw();
   client_->SetNeedsAnimateOnImplThread();
@@ skipping 1482 matching lines @@
   new_target.SetToMin(layer_impl->MaxScrollOffset());
 
   curve->UpdateTarget(
       animation->TrimTimeToCurrentIteration(CurrentBeginFrameArgs().frame_time)
           .InSecondsF(),
       new_target);
 
   return true;
 }
 }  // namespace cc