content/ui[Android]: Remove ContextProviderFactory.

services/ui/public/cpp/gpu/gpu.cc

Index: services/ui/public/cpp/gpu/gpu.cc
diff --git a/services/ui/public/cpp/gpu/gpu.cc b/services/ui/public/cpp/gpu/gpu.cc
index 06238988ac9cfa9d4b02527955740b3cf5a3a21e..8634525475b22fab3be96ca8a462df75e081168d 100644
--- a/services/ui/public/cpp/gpu/gpu.cc
+++ b/services/ui/public/cpp/gpu/gpu.cc
@@ -46,6 +46,9 @@ Gpu::Gpu(service_manager::Connector* connector,
 
 Gpu::~Gpu() {
   DCHECK(IsMainThread());
+  DCHECK(!in_shutdown_);
+
+  in_shutdown_ = true;
   for (const auto& callback : establish_callbacks_)
     callback.Run(nullptr);
   shutdown_event_.Signal();
@@ -90,6 +93,10 @@ scoped_refptr<cc::ContextProvider> Gpu::CreateContextProvider(
 void Gpu::EstablishGpuChannel(
     const gpu::GpuChannelEstablishedCallback& callback) {
   DCHECK(IsMainThread());
+
+  if (in_shutdown_)
+    return;
+
   scoped_refptr<gpu::GpuChannelHost> channel = GetGpuChannel();
   if (channel) {
     main_task_runner_->PostTask(FROM_HERE,