Remove GPU relinquish resources infrastructure and stop GPU process.

content/browser/gpu/gpu_process_host.h

Index: content/browser/gpu/gpu_process_host.h
diff --git a/content/browser/gpu/gpu_process_host.h b/content/browser/gpu/gpu_process_host.h
index 7df522a80b6c87619432e93ae66af269643e03a4..b5830da72de70934bfd2310c36ca8d2e8a7799ae 100644
--- a/content/browser/gpu/gpu_process_host.h
+++ b/content/browser/gpu/gpu_process_host.h
@@ -141,8 +141,12 @@ class GpuProcessHost : public BrowserChildProcessHostDelegate,
   // What kind of GPU process, e.g. sandboxed or unsandboxed.
   GpuProcessKind kind();
 
+  // Forcefully terminates the GPU process.
   void ForceShutdown();
 
+  // Asks the GPU process to stop by itself.
+  void StopGpuProcess();
+
   void BeginFrameSubscription(
       int surface_id,
       base::WeakPtr<RenderWidgetHostViewFrameSubscriber> subscriber);
@@ -235,6 +239,9 @@ class GpuProcessHost : public BrowserChildProcessHostDelegate,
   // Whether the GPU process successfully initialized.
   bool initialized_;
 
+  // Whether the GPU process is shutting down or not.
+  bool expecting_shutdown_;
+
   // Time Init started.  Used to log total GPU process startup time to UMA.
   base::TimeTicks init_start_time_;