CC: Fix call order of ScrollOffsetDelegate in ActivatePendingTree.

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 "base/basictypes.h"
@@ skipping 1523 matching lines @@
   // the swap.
   pending_tree_->ProcessUIResourceRequestQueue();
 
   pending_tree_->PushPropertiesTo(active_tree_.get());
 
   // Now that we've synced everything from the pending tree to the active
   // tree, rename the pending tree the recycle tree so we can reuse it on the
   // next sync.
   pending_tree_.swap(recycle_tree_);
 
+  active_tree_->DidBecomeActive();
   active_tree_->SetRootLayerScrollOffsetDelegate(
       root_layer_scroll_offset_delegate_);
-  active_tree_->DidBecomeActive();
 
   // Reduce wasted memory now that unlinked resources are guaranteed not
   // to be used.
   client_->ReduceWastedContentsTextureMemoryOnImplThread();
 
   client_->OnCanDrawStateChanged(CanDraw());
   client_->SetNeedsRedrawOnImplThread();
   client_->RenewTreePriority();
 
   if (debug_state_.continuous_painting) {
@@ skipping 1230 matching lines @@
   std::set<UIResourceId>::iterator found_in_evicted =
       evicted_ui_resources_.find(uid);
   if (found_in_evicted == evicted_ui_resources_.end())
     return;
   evicted_ui_resources_.erase(found_in_evicted);
   if (evicted_ui_resources_.empty())
     client_->OnCanDrawStateChanged(CanDraw());
 }
 
 }  // namespace cc