Replaced is_null() with is_valid in SurfaceId and related classes.

components/exo/surface.cc

Index: components/exo/surface.cc
diff --git a/components/exo/surface.cc b/components/exo/surface.cc
index 5f22ec6fd64ad5a361039368515743886f0a1530..fe7f25695f62033ef9a9339adc591f13c7d3954d 100644
--- a/components/exo/surface.cc
+++ b/components/exo/surface.cc
@@ -239,7 +239,7 @@ Surface::~Surface() {
   for (const auto& frame_callback : active_frame_callbacks_)
     frame_callback.Run(base::TimeTicks());
 
-  if (!local_frame_id_.is_null())
+  if (local_frame_id_.is_valid())
     factory_owner_->surface_factory_->Destroy(local_frame_id_);
 }
 
@@ -446,7 +446,7 @@ void Surface::Commit() {
 }
 
 void Surface::OnLostResources() {
-  if (local_frame_id_.is_null())
+  if (!local_frame_id_.is_valid())
     return;
 
   UpdateResource(false);
@@ -471,7 +471,7 @@ void Surface::CommitSurfaceHierarchy() {
   }
 
   cc::LocalFrameId old_local_frame_id = local_frame_id_;
-  if (needs_commit_to_new_surface_ || local_frame_id_.is_null()) {
+  if (needs_commit_to_new_surface_ || !local_frame_id_.is_valid()) {
     needs_commit_to_new_surface_ = false;
     local_frame_id_ = factory_owner_->id_allocator_->GenerateId();
     factory_owner_->surface_factory_->Create(local_frame_id_);
@@ -479,7 +479,7 @@ void Surface::CommitSurfaceHierarchy() {
 
   UpdateSurface(true);
 
-  if (!old_local_frame_id.is_null() && old_local_frame_id != local_frame_id_) {
+  if (old_local_frame_id.is_valid() && old_local_frame_id != local_frame_id_) {
     factory_owner_->surface_factory_->SetPreviousFrameSurface(
         local_frame_id_, old_local_frame_id);
     factory_owner_->surface_factory_->Destroy(old_local_frame_id);
@@ -695,7 +695,7 @@ void Surface::SetSurfaceHierarchyNeedsCommitToNewSurfaces() {
 }
 
 void Surface::SetSurfaceLayerContents(ui::Layer* layer) {
-  if (local_frame_id_.is_null())
+  if (!local_frame_id_.is_valid())
     return;
 
   gfx::Size layer_size = layer->bounds().size();