Remove GPU relinquish resources infrastructure and stop GPU process.

ui/ozone/public/gpu_platform_support.cc

Index: ui/ozone/public/gpu_platform_support.cc
diff --git a/ui/ozone/public/gpu_platform_support.cc b/ui/ozone/public/gpu_platform_support.cc
index 0f3e8a1f7f9e960e2d2192c1bd3f3c41069b8866..ec6157ea446087178dda7d13e94c71d208873e53 100644
--- a/ui/ozone/public/gpu_platform_support.cc
+++ b/ui/ozone/public/gpu_platform_support.cc
@@ -17,15 +17,9 @@ class StubGpuPlatformSupport : public GpuPlatformSupport {
   // GpuPlatformSupport:
   void OnChannelEstablished(IPC::Sender* sender) override {}
   bool OnMessageReceived(const IPC::Message&) override { return false; }
-  void RelinquishGpuResources(const base::Closure& callback) override;
   IPC::MessageFilter* GetMessageFilter() override { return nullptr; }
 };
 
-void StubGpuPlatformSupport::RelinquishGpuResources(
-    const base::Closure& callback) {
-  callback.Run();
-}
-
 }  // namespace
 
 GpuPlatformSupport::GpuPlatformSupport() {