Update page scale factor in property before calling ComputeVisibleRects

When page scale factor is updated directly on the active tree using
LayerTreeImpl::SetPageScaleOnActiveTree, the property trees on pending
tree are not updated. At this point, if we compute draw properties on
pending tree, there is a mismatch between the properties computed from
property trees and CDP because CDP uses the new value (as page scale
factor itself is a synced property) and pending tree property trees
use the old value.
This CL updates page scale factor in property trees before we call
ComputeVisibleRectsUsingPropertyTrees.

BUG=538624
CQ_INCLUDE_TRYBOTS=tryserver.blink:linux_blink_rel

Review URL: https://codereview.chromium.org/1382353004

Cr-Commit-Position: refs/heads/master@{#352888}

1 files changed, 7 insertions, 0 deletions

diff --git a/cc/trees/layer_tree_host_common.cc b/cc/trees/layer_tree_host_common.cc
index 2d2bd3e..21054ff 100644
--- a/cc/trees/layer_tree_host_common.cc
+++ b/cc/trees/layer_tree_host_common.cc
@@ -2709,6 +2709,13 @@ void CalculateDrawPropertiesAndVerify(
         TRACE_EVENT0(
             TRACE_DISABLED_BY_DEFAULT("cc.debug.cdp-perf"),
             "LayerTreeHostCommon::ComputeJustVisibleRectsWithPropertyTrees");
+        // Since page scale is a SyncedProperty, changes to page scale on the
+        // active tree immediately affect the pending tree, so instead of
+        // trying to update property trees whenever page scale changes, we
+        // update their page scale before using them.
+        UpdatePageScaleFactorInPropertyTrees(inputs->property_trees,
+                                             inputs->page_scale_layer,
+                                             inputs->page_scale_factor);
         ComputeVisibleRectsUsingPropertyTrees(
             inputs->root_layer, inputs->property_trees, &update_layer_list);
         break;