cc: PushProperties on viewport size change

cc/trees/layer_tree_host.cc

Index: cc/trees/layer_tree_host.cc
diff --git a/cc/trees/layer_tree_host.cc b/cc/trees/layer_tree_host.cc
index 5b656a8f7363adb04b77919df722098ecb258218..8c6eeef76452e7cdaffaaa041997487d4e1e6a73 100644
--- a/cc/trees/layer_tree_host.cc
+++ b/cc/trees/layer_tree_host.cc
@@ -343,6 +343,18 @@ void LayerTreeHost::FinishCommitOnImplThread(LayerTreeHostImpl* host_impl) {
   host_impl->set_gpu_rasterization_status(GetGpuRasterizationStatus());
   RecordGpuRasterizationHistogram();
 
+  // When we are using GPU rasterization, tile size is based on the viewport
+  // width.  We could have layers that change in size, but are not invalidated
+  // because no layout is required.  When this happens, we need to notify the
+  // layers that they require a PushProperties to resize the tiles correctly.
+  if (root_layer() &&
+      device_viewport_size_ != host_impl->device_viewport_size() &&
+      UseGpuRasterization()) {
+    LayerTreeHostCommon::CallFunctionForSubtree(root_layer(), [](Layer* layer) {
+      layer->OnDeviceViewportSizeChanged();
+    });
+  }
+
   host_impl->SetViewportSize(device_viewport_size_);
   host_impl->SetDeviceScaleFactor(device_scale_factor_);
   host_impl->SetDebugState(debug_state_);