Revert of Fix potential shutdown deadlock in UI service

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

Index: services/ui/public/cpp/gpu/client_gpu_memory_buffer_manager.cc
diff --git a/services/ui/public/cpp/gpu/client_gpu_memory_buffer_manager.cc b/services/ui/public/cpp/gpu/client_gpu_memory_buffer_manager.cc
index efff978265a194c569cf66a21390ef61eb3c0bee..e91fce823c9a275b56d5c4d4c2ac701edd965d31 100644
--- a/services/ui/public/cpp/gpu/client_gpu_memory_buffer_manager.cc
+++ b/services/ui/public/cpp/gpu/client_gpu_memory_buffer_manager.cc
@@ -21,6 +21,13 @@
 namespace ui {
 
 namespace {
+
+void OnGpuMemoryBufferAllocated(gfx::GpuMemoryBufferHandle* ret_handle,
+                                base::WaitableEvent* wait,
+                                const gfx::GpuMemoryBufferHandle& handle) {
+  *ret_handle = handle;
+  wait->Signal();
+}
 
 void NotifyDestructionOnCorrectThread(
     scoped_refptr<base::SingleThreadTaskRunner> task_runner,
@@ -51,24 +58,12 @@
 
 void ClientGpuMemoryBufferManager::InitThread(mojom::GpuPtrInfo gpu_info) {
   gpu_.Bind(std::move(gpu_info));
-  gpu_.set_connection_error_handler(
-      base::Bind(&ClientGpuMemoryBufferManager::DisconnectGpuOnThread,
-                 base::Unretained(this)));
   weak_ptr_ = weak_ptr_factory_.GetWeakPtr();
 }
 
 void ClientGpuMemoryBufferManager::TearDownThread() {
   weak_ptr_factory_.InvalidateWeakPtrs();
-  DisconnectGpuOnThread();
-}
-
-void ClientGpuMemoryBufferManager::DisconnectGpuOnThread() {
-  if (!gpu_.is_bound())
-    return;
   gpu_.reset();
-  for (auto& waiter : pending_allocation_waiters_)
-    waiter->Signal();
-  pending_allocation_waiters_.clear();
 }
 
 void ClientGpuMemoryBufferManager::AllocateGpuMemoryBufferOnThread(
@@ -81,24 +76,9 @@
   // |handle| and |wait| are both on the stack, and will be alive until |wait|
   // is signaled. So it is safe for OnGpuMemoryBufferAllocated() to operate on
   // these.
-  pending_allocation_waiters_.insert(wait);
   gpu_->CreateGpuMemoryBuffer(
       gfx::GpuMemoryBufferId(++counter_), size, format, usage,
-      base::Bind(
-          &ClientGpuMemoryBufferManager::OnGpuMemoryBufferAllocatedOnThread,
-          base::Unretained(this), handle, wait));
-}
-
-void ClientGpuMemoryBufferManager::OnGpuMemoryBufferAllocatedOnThread(
-    gfx::GpuMemoryBufferHandle* ret_handle,
-    base::WaitableEvent* wait,
-    const gfx::GpuMemoryBufferHandle& handle) {
-  auto it = pending_allocation_waiters_.find(wait);
-  DCHECK(it != pending_allocation_waiters_.end());
-  pending_allocation_waiters_.erase(it);
-
-  *ret_handle = handle;
-  wait->Signal();
+      base::Bind(&OnGpuMemoryBufferAllocated, handle, wait));
 }
 
 void ClientGpuMemoryBufferManager::DeletedGpuMemoryBuffer(