Setup DiscardableMemory in the ash process

ui/aura/mus/window_tree_client.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 "ui/aura/mus/window_tree_client.h"
 
 #include <stddef.h>
 
 #include <string>
 #include <utility>
 #include <vector>
 
 #include "base/auto_reset.h"
 #include "base/bind.h"
 #include "base/memory/ptr_util.h"
+#include "base/threading/thread.h"
+#include "components/discardable_memory/client/client_discardable_shared_memory_manager.h"
 #include "mojo/public/cpp/bindings/map.h"
 #include "services/service_manager/public/cpp/connector.h"
 #include "services/ui/common/accelerator_util.h"
 #include "services/ui/public/cpp/gpu/gpu.h"
 #include "services/ui/public/cpp/property_type_converters.h"
 #include "services/ui/public/interfaces/constants.mojom.h"
 #include "services/ui/public/interfaces/window_manager.mojom.h"
 #include "services/ui/public/interfaces/window_manager_window_tree_factory.mojom.h"
 #include "ui/aura/client/aura_constants.h"
 #include "ui/aura/client/drag_drop_client.h"
@@ skipping 142 matching lines @@
   GetWindowTreeHostMus(target)->SendEventToProcessor(event);
 }
 
 }  // namespace
 
 WindowTreeClient::WindowTreeClient(
     service_manager::Connector* connector,
     WindowTreeClientDelegate* delegate,
     WindowManagerDelegate* window_manager_delegate,
     mojo::InterfaceRequest<ui::mojom::WindowTreeClient> request,
-    scoped_refptr<base::SingleThreadTaskRunner> io_task_runner)
+    scoped_refptr<base::SingleThreadTaskRunner> io_task_runner,
+    bool create_discardable_memory)
     : connector_(connector),
       client_id_(0),
       next_window_id_(1),
       next_change_id_(1),
       delegate_(delegate),
       window_manager_delegate_(window_manager_delegate),
       binding_(this),
       tree_(nullptr),
       in_destructor_(false),
       weak_factory_(this) {
   DCHECK(delegate_);
   // Allow for a null request in tests.
   if (request.is_pending())
     binding_.Bind(std::move(request));
   client::GetTransientWindowClient()->AddObserver(this);
   if (window_manager_delegate)
     window_manager_delegate->SetWindowManagerClient(this);
   if (connector) {  // |connector| can be null in tests.
-    gpu_ = ui::Gpu::Create(connector, std::move(io_task_runner));
+    if (!io_task_runner) {
+      // |io_task_runner| is null in most case. But for the browser process,
+      // the |io_task_runner| is the browser's IO thread.
+      io_thread_ = base::MakeUnique<base::Thread>("IOThread");
+      base::Thread::Options thread_options(base::MessageLoop::TYPE_IO, 0);
+      thread_options.priority = base::ThreadPriority::NORMAL;
+      CHECK(io_thread_->StartWithOptions(thread_options));
+      io_task_runner = io_thread_->task_runner();
+    }
+
+    gpu_ = ui::Gpu::Create(connector, io_task_runner);
     compositor_context_factory_ =
         base::MakeUnique<MusContextFactory>(gpu_.get());
     initial_context_factory_ = Env::GetInstance()->context_factory();
     Env::GetInstance()->set_context_factory(compositor_context_factory_.get());
+
+    // WindowServerTest will create more than one WindowTreeClient. We will not
+    // create the discardable memory manager for those tests.
+    if (create_discardable_memory) {
+      discardable_memory::mojom::DiscardableSharedMemoryManagerPtr manager_ptr;
+      connector->BindInterface(ui::mojom::kServiceName, &manager_ptr);
+      discardable_shared_memory_manager_ = base::MakeUnique<
+          discardable_memory::ClientDiscardableSharedMemoryManager>(
+          std::move(manager_ptr), std::move(io_task_runner));
+      base::DiscardableMemoryAllocator::SetInstance(
+          discardable_shared_memory_manager_.get());
+    }
   }
 }
 
 WindowTreeClient::~WindowTreeClient() {
   in_destructor_ = true;
 
+  if (discardable_shared_memory_manager_)

[sky, 2017/03/14 03:15:34]

Should this be null'd out after the thread is shutdown?

[Peng, 2017/03/14 15:03:14]

SetInstance(nullptr) will prevent the manager being used anymore. And we have to
delete the manager before the shutdown the IO thread. See[1], the manager uses
the IOThread to destroy the mojo interface ptr.

[1]https://cs.chromium.org/chromium/src/components/discardable_memory/client/client_discardable_shared_memory_manager.cc?rcl=5a17deed92877ccc6589dcde406a32a5d21756a5&l=130

+    base::DiscardableMemoryAllocator::SetInstance(nullptr);
+
   for (WindowTreeClientObserver& observer : observers_)
     observer.OnWillDestroyClient(this);
 
   // Clients should properly delete all of their windows before shutdown.
   CHECK(windows_.empty());
 
   capture_synchronizer_.reset();
 
   client::GetTransientWindowClient()->RemoveObserver(this);
 
@@ skipping 1605 matching lines @@
   return ScheduleInFlightChange(base::MakeUnique<InFlightCaptureChange>(
       this, capture_synchronizer_.get(), window));
 }
 
 uint32_t WindowTreeClient::CreateChangeIdForFocus(WindowMus* window) {
   return ScheduleInFlightChange(base::MakeUnique<InFlightFocusChange>(
       this, focus_synchronizer_.get(), window));
 }
 
 }  // namespace aura