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

cc/surfaces/direct_compositor_frame_sink.cc

 // Copyright 2014 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "cc/surfaces/direct_compositor_frame_sink.h"
 
 #include "base/bind.h"
 #include "cc/output/compositor_frame.h"
 #include "cc/output/compositor_frame_sink_client.h"
 #include "cc/surfaces/display.h"
@@ skipping 60 matching lines @@
   // Avoid initializing GL context here, as this should be sharing the
   // Display's context.
   display_->Initialize(this, surface_manager_, frame_sink_id_);
   return true;
 }
 
 void DirectCompositorFrameSink::DetachFromClient() {
   // Unregister the SurfaceFactoryClient here instead of the dtor so that only
   // one client is alive for this namespace at any given time.
   surface_manager_->UnregisterSurfaceFactoryClient(frame_sink_id_);
-  if (!delegated_local_frame_id_.is_null())
+  if (delegated_local_frame_id_.is_valid())
     factory_.Destroy(delegated_local_frame_id_);
 
   CompositorFrameSink::DetachFromClient();
 }
 
 void DirectCompositorFrameSink::SubmitCompositorFrame(CompositorFrame frame) {
   gfx::Size frame_size =
       frame.delegated_frame_data->render_pass_list.back()->output_rect.size();
   if (frame_size.IsEmpty() || frame_size != last_swap_frame_size_) {
-    if (!delegated_local_frame_id_.is_null()) {
+    if (delegated_local_frame_id_.is_valid()) {
       factory_.Destroy(delegated_local_frame_id_);
     }
     delegated_local_frame_id_ = surface_id_allocator_.GenerateId();
     factory_.Create(delegated_local_frame_id_);
     last_swap_frame_size_ = frame_size;
   }
   display_->SetSurfaceId(SurfaceId(frame_sink_id_, delegated_local_frame_id_),
                          frame.metadata.device_scale_factor);
 
   factory_.SubmitCompositorFrame(
       delegated_local_frame_id_, std::move(frame),
       base::Bind(&DirectCompositorFrameSink::DidDrawCallback,
                  base::Unretained(this)));
 }
 
 void DirectCompositorFrameSink::ForceReclaimResources() {
-  if (!delegated_local_frame_id_.is_null()) {
+  if (delegated_local_frame_id_.is_valid()) {
     factory_.SubmitCompositorFrame(delegated_local_frame_id_, CompositorFrame(),
                                    SurfaceFactory::DrawCallback());
   }
 }
 
 void DirectCompositorFrameSink::ReturnResources(
     const ReturnedResourceArray& resources) {
   if (client_)
     client_->ReclaimResources(resources);
 }
@@ skipping 19 matching lines @@
   // This notification is not relevant to our client outside of tests. We
   // unblock the client from DidDrawCallback() when the surface is going to
   // be drawn.
 }
 
 void DirectCompositorFrameSink::DidDrawCallback() {
   client_->DidReceiveCompositorFrameAck();
 }
 
 }  // namespace cc