Refactor delta/sent_delta logic into self-contained abstraction.

This patch updates page scale to use a new SyncedProperty abstraction.  This
is shared between the pending and active trees and contains all page scale state
on the impl side except for the min/max limits.  Its API only exposes those
operations that are encouraged: for example, the raw main-thread originating value
can no longer be used by accident.

This patch should be a no-op.  In future patches, I intend to make scroll offsets
and top controls use this abstraction as well.

NOTRY=true
BUG=

Review URL: https://codereview.chromium.org/764483002

Cr-Commit-Position: refs/heads/master@{#306736}

1 files changed, 4 insertions, 2 deletions

diff --git a/cc/trees/layer_tree_impl_unittest.cc b/cc/trees/layer_tree_impl_unittest.cc
index 52f8e0a..2131d4c 100644
--- a/cc/trees/layer_tree_impl_unittest.cc
+++ b/cc/trees/layer_tree_impl_unittest.cc
@@ -1795,8 +1795,9 @@ TEST_F(LayerTreeImplTest,
   host_impl().SetViewportSize(scaled_bounds_for_root);
 
   host_impl().SetDeviceScaleFactor(device_scale_factor);
-  host_impl().active_tree()->SetPageScaleFactorAndLimits(
+  host_impl().active_tree()->PushPageScaleFromMainThread(
       page_scale_factor, page_scale_factor, page_scale_factor);
+  host_impl().SetPageScaleOnActiveTree(page_scale_factor);
   host_impl().active_tree()->SetRootLayer(root.Pass());
   host_impl().active_tree()->SetViewportLayersFromIds(Layer::INVALID_ID, 1, 1,
                                                       Layer::INVALID_ID);
@@ -2299,8 +2300,9 @@ TEST_F(LayerTreeImplTest, SelectionBoundsForScaledLayers) {
   host_impl().SetViewportSize(scaled_bounds_for_root);
 
   host_impl().SetDeviceScaleFactor(device_scale_factor);
-  host_impl().active_tree()->SetPageScaleFactorAndLimits(
+  host_impl().active_tree()->PushPageScaleFromMainThread(
       page_scale_factor, page_scale_factor, page_scale_factor);
+  host_impl().SetPageScaleOnActiveTree(page_scale_factor);
   host_impl().active_tree()->SetRootLayer(root.Pass());
   host_impl().active_tree()->SetViewportLayersFromIds(Layer::INVALID_ID, 1, 1,
                                                       Layer::INVALID_ID);