Update from https://crrev.com/314320

cc/base/synced_property.h

 // Copyright 2014 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.
 
 #ifndef CC_BASE_SYNCED_PROPERTY_H_
 #define CC_BASE_SYNCED_PROPERTY_H_
 
 #include "base/memory/ref_counted.h"
 
 namespace cc {
@@ skipping 79 matching lines @@
 
   // This simulates the consequences of the sent value getting committed and
   // activated.  The value sent to the main thread ends up combined with the
   // active value, and the sent_delta is subtracted from the delta.
   void AbortCommit() {
     active_base_ = active_base_.Combine(sent_delta_);
     active_delta_ = PendingDelta();
     sent_delta_ = T::Identity();
   }
 
- private:
+  // Values as last pushed to the pending or active tree respectively, with no
+  // impl-thread delta applied.
+  typename T::ValueType PendingBase() const { return pending_base_.get(); }
+  typename T::ValueType ActiveBase() const { return active_base_.get(); }
+
   // The new delta we would use if we decide to activate now.  This delta
   // excludes the amount that we expect the main thread to reflect back at the
   // impl thread during the commit.
   T PendingDelta() const { return active_delta_.InverseCombine(sent_delta_); }
 
+ private:
   // Value last committed to the pending tree.
   T pending_base_;
   // Value last committed to the active tree (on the last activation).
   T active_base_;
   // The difference between the active_base_ and the user-perceived value.
   T active_delta_;
   // The value sent to the main thread (on the last BeginFrame); this is always
   // identity outside of the BeginFrame-to-activation interval.
   T sent_delta_;
 
@@ skipping 47 matching lines @@
     return ScaleGroup(value_ / p.value_);
   }
 
  private:
   float value_;
 };
 
 }  // namespace cc
 
 #endif  // CC_BASE_SYNCED_PROPERTY_H_