Make PageScaleFactor work for oopif subframes.

cc/trees/layer_tree_host_impl.cc

Index: cc/trees/layer_tree_host_impl.cc
diff --git a/cc/trees/layer_tree_host_impl.cc b/cc/trees/layer_tree_host_impl.cc
index 915f7ea72f25aaea11529420ca982b2b29ed0de3..0b11e6e4a5be27433d1d87ac4d3dd7e028297577 100644
--- a/cc/trees/layer_tree_host_impl.cc
+++ b/cc/trees/layer_tree_host_impl.cc
@@ -265,8 +265,8 @@ LayerTreeHostImpl::LayerTreeHostImpl(
 
   // LTHI always has an active tree.
   active_tree_ = base::MakeUnique<LayerTreeImpl>(
-      this, new SyncedProperty<ScaleGroup>, new SyncedBrowserControls,
-      new SyncedElasticOverscroll);
+      this, new SyncedProperty<ScaleGroup>, new SyncedProperty<ScaleGroup>,
+      new SyncedBrowserControls, new SyncedElasticOverscroll);
   active_tree_->property_trees()->is_active = true;
 
   viewport_ = Viewport::Create(this);
@@ -1198,10 +1198,11 @@ void LayerTreeHostImpl::BlockNotifyReadyToActivateForTesting(bool block) {
 void LayerTreeHostImpl::ResetTreesForTesting() {
   if (active_tree_)
     active_tree_->DetachLayers();
-  active_tree_ =
-      base::MakeUnique<LayerTreeImpl>(this, active_tree()->page_scale_factor(),
-                                      active_tree()->top_controls_shown_ratio(),
-                                      active_tree()->elastic_overscroll());
+  active_tree_ = base::MakeUnique<LayerTreeImpl>(
+      this, active_tree()->page_scale_factor(),
+      active_tree()->subframe_page_scale_factor(),
+      active_tree()->top_controls_shown_ratio(),
+      active_tree()->elastic_overscroll());
   active_tree_->property_trees()->is_active = true;
   if (pending_tree_)
     pending_tree_->DetachLayers();
@@ -1541,6 +1542,7 @@ CompositorFrameMetadata LayerTreeHostImpl::MakeCompositorFrameMetadata() const {
                                  active_tree_->device_scale_factor();
 
   metadata.page_scale_factor = active_tree_->current_page_scale_factor();
+  // TODO(wjmaclean): Should we sxpose subframe PSF here?
   metadata.scrollable_viewport_size = active_tree_->ScrollableViewportSize();
   metadata.root_layer_size = active_tree_->ScrollableSize();
   metadata.min_page_scale_factor = active_tree_->min_page_scale_factor();
@@ -1952,6 +1954,7 @@ void LayerTreeHostImpl::CreatePendingTree() {
   } else {
     pending_tree_ = base::MakeUnique<LayerTreeImpl>(
         this, active_tree()->page_scale_factor(),
+        active_tree()->subframe_page_scale_factor(),
         active_tree()->top_controls_shown_ratio(),
         active_tree()->elastic_overscroll());
   }
@@ -3318,9 +3321,14 @@ void LayerTreeHostImpl::PinchGestureBegin() {
 void LayerTreeHostImpl::PinchGestureUpdate(float magnify_delta,
                                            const gfx::Point& anchor) {
   TRACE_EVENT0("cc", "LayerTreeHostImpl::PinchGestureUpdate");
-  if (!InnerViewportScrollLayer())
-    return;
-  viewport()->PinchUpdate(magnify_delta, anchor);
+  if (InnerViewportScrollLayer()) {
+    viewport()->PinchUpdate(magnify_delta, anchor);
+  } else {
+    float subframe_page_scale_factor =
+        active_tree_->GetSubframePageScaleFactor();
+    subframe_page_scale_factor *= magnify_delta;
+    active_tree_->SetSubframePageScaleOnActiveTree(subframe_page_scale_factor);
+  }
   client_->SetNeedsCommitOnImplThread();
   SetNeedsRedraw();
   client_->RenewTreePriority();