mus::GpuService: Support establish GpuChannel asynchronously.

components/mus/common/gpu_service.cc

Index: components/mus/common/gpu_service.cc
diff --git a/components/mus/common/gpu_service.cc b/components/mus/common/gpu_service.cc
index c3b15ff7cbf367a08a042f556ee07bd6f3771316..4eea3e45972eef52d0efb41548cab1860adbe77f 100644
--- a/components/mus/common/gpu_service.cc
+++ b/components/mus/common/gpu_service.cc
@@ -9,7 +9,6 @@
 #include "base/threading/thread_task_runner_handle.h"
 #include "build/build_config.h"
 #include "components/mus/common/gpu_type_converters.h"
-#include "components/mus/common/mojo_gpu_memory_buffer_manager.h"
 #include "components/mus/common/switches.h"
 #include "components/mus/public/interfaces/gpu_service.mojom.h"
 #include "mojo/public/cpp/bindings/sync_call_restrictions.h"
@@ -18,18 +17,38 @@
 
 namespace mus {
 
-GpuService::GpuService()
+namespace {
+
+void PostTask(scoped_refptr<base::SingleThreadTaskRunner> runner,
+              const tracked_objects::Location& from_here,
+              const base::Closure& callback) {
+  runner->PostTask(from_here, callback);
+}
+
+GpuService* g_gpu_service = nullptr;
+}
+
+GpuService::GpuService(shell::Connector* connector)
     : main_task_runner_(base::ThreadTaskRunnerHandle::Get()),
+      connector_(connector),
       shutdown_event_(base::WaitableEvent::ResetPolicy::AUTOMATIC,
                       base::WaitableEvent::InitialState::NOT_SIGNALED),
       io_thread_("GPUIOThread"),
-      gpu_memory_buffer_manager_(new MojoGpuMemoryBufferManager) {
+      gpu_memory_buffer_manager_(new MojoGpuMemoryBufferManager),
+      is_establishing_(false),
+      establishing_condition_(&lock_) {
+  DCHECK(main_task_runner_);
+  DCHECK(connector_);
   base::Thread::Options thread_options(base::MessageLoop::TYPE_IO, 0);
   thread_options.priority = base::ThreadPriority::NORMAL;
   CHECK(io_thread_.StartWithOptions(thread_options));
 }
 
-GpuService::~GpuService() {}
+GpuService::~GpuService() {
+  DCHECK(IsMainThread());
+  if (gpu_channel_)
+    gpu_channel_->DestroyChannel();
+}
 
 // static
 bool GpuService::UseChromeGpuCommandBuffer() {
@@ -44,45 +63,166 @@ bool GpuService::UseChromeGpuCommandBuffer() {
 }
 
 // static
+void GpuService::Initialize(shell::Connector* connector) {
+  DCHECK(!g_gpu_service);
+  g_gpu_service = new GpuService(connector);
+}
+
+// static
+void GpuService::Terminate() {
+  DCHECK(g_gpu_service);
+  delete g_gpu_service;
+  g_gpu_service = nullptr;
+}
+
+// static
 GpuService* GpuService::GetInstance() {
-  return base::Singleton<GpuService,
-                         base::LeakySingletonTraits<GpuService>>::get();
+  DCHECK(g_gpu_service);
+  return g_gpu_service;
+}
+
+void GpuService::EstablishGpuChannel(const base::Closure& callback) {
+  base::AutoLock auto_lock(lock_);
+  auto runner = base::ThreadTaskRunnerHandle::Get();
+  if (GetGpuChannelLocked()) {
+    runner->PostTask(FROM_HERE, callback);
+    return;
+  }
+
+  base::Closure wrapper_callback =
+      IsMainThread() ? callback
+                     : base::Bind(PostTask, runner, FROM_HERE, callback);
+  establish_callbacks_.push_back(wrapper_callback);
+
+  if (!is_establishing_) {
+    is_establishing_ = true;
+    main_task_runner_->PostTask(
+        FROM_HERE, base::Bind(&GpuService::EstablishGpuChannelOnMainThread,
+                              base::Unretained(this)));
+  }
 }
 
-scoped_refptr<gpu::GpuChannelHost> GpuService::EstablishGpuChannel(
-    shell::Connector* connector) {
+scoped_refptr<gpu::GpuChannelHost> GpuService::EstablishGpuChannelSync() {
   base::AutoLock auto_lock(lock_);
+  if (GetGpuChannelLocked())
+    return gpu_channel_;
+
+  if (IsMainThread()) {
+    is_establishing_ = true;
+    EstablishGpuChannelOnMainThreadSyncLocked();
+  } else {
+    if (!is_establishing_) {
+      // Create an establishing gpu channel task, if there isn't one.
+      is_establishing_ = true;
+      main_task_runner_->PostTask(
+          FROM_HERE, base::Bind(&GpuService::EstablishGpuChannelOnMainThread,
+                                base::Unretained(this)));
+    }
+
+    // Wait until the pending establishing task is finished.
+    do {
+      establishing_condition_.Wait();
+    } while (is_establishing_);
+  }
+  return gpu_channel_;
+}
+
+scoped_refptr<gpu::GpuChannelHost> GpuService::GetGpuChannel() {
+  base::AutoLock auto_lock(lock_);
+  return GetGpuChannelLocked();
+}
+
+scoped_refptr<gpu::GpuChannelHost> GpuService::GetGpuChannelLocked() {
   if (gpu_channel_ && gpu_channel_->IsLost()) {
-    gpu_channel_->DestroyChannel();
+    main_task_runner_->PostTask(
+        FROM_HERE,
+        base::Bind(&gpu::GpuChannelHost::DestroyChannel, gpu_channel_));
     gpu_channel_ = nullptr;
   }
+  return gpu_channel_;
+}
 
-  if (gpu_channel_)
-    return gpu_channel_;
+void GpuService::EstablishGpuChannelOnMainThread() {
+  base::AutoLock auto_lock(lock_);
+  DCHECK(IsMainThread());
+
+  // In GpuService::EstablishGpuChannelOnMainThreadSyncLocked(), we use the sync
+  // mojo EstablishGpuChannel call, after that call the gpu_service_ will be
+  // reset immediatelly. So gpu_service_ should be always null here.
+  DCHECK(!gpu_service_);
+
+  // is_establishing_ is false, it means GpuService::EstablishGpuChannelSync()
+  // has been used, and we don't need try to establish a new GPU channel
+  // anymore.
+  if (!is_establishing_)
+    return;
+
+  connector_->ConnectToInterface("mojo:mus", &gpu_service_);
+  const bool locked = false;
+  gpu_service_->EstablishGpuChannel(
+      base::Bind(&GpuService::EstablishGpuChannelOnMainThreadDone,
+                 base::Unretained(this), locked));
+}
+
+void GpuService::EstablishGpuChannelOnMainThreadSyncLocked() {
+  DCHECK(IsMainThread());
+  DCHECK(is_establishing_);
 
-  mus::mojom::GpuServicePtr gpu_service;
-  connector->ConnectToInterface("mojo:mus", &gpu_service);
+  // In browser process, EstablishGpuChannelSync() is only used by testing &
+  // GpuProcessTransportFactory::GetGLHelper(). For GetGLHelper(), it expects
+  // the gpu channel has been established, so it should not reach here.
+  // For testing, the  asyc method should not be used.
+  // In renderer process, we only use EstablishGpuChannelSync().
+  // So the gpu_service_ should be null here.
+  DCHECK(!gpu_service_);
 
   int client_id = 0;
   mojom::ChannelHandlePtr channel_handle;
   mojom::GpuInfoPtr gpu_info;
+  connector_->ConnectToInterface("mojo:mus", &gpu_service_);
   {
-    // TODO(penghuang): Remove the ScopedAllowSyncCall when HW rendering is
-    // enabled in mus chrome.
+    base::AutoUnlock auto_unlock(lock_);
     mojo::SyncCallRestrictions::ScopedAllowSyncCall allow_sync_call;
-    if (!gpu_service->EstablishGpuChannel(&client_id, &channel_handle,
-                                          &gpu_info)) {
+    if (!gpu_service_->EstablishGpuChannel(&client_id, &channel_handle,
+                                           &gpu_info)) {
       DLOG(WARNING)
           << "Channel encountered error while establishing gpu channel.";
-      return nullptr;
+      return;
     }
   }
+  const bool locked = true;
+  EstablishGpuChannelOnMainThreadDone(
+      locked, client_id, std::move(channel_handle), std::move(gpu_info));
+}
 
-  // TODO(penghuang): Get the real gpu info from mus.
-  gpu_channel_ = gpu::GpuChannelHost::Create(
-      this, client_id, gpu::GPUInfo(), channel_handle.To<IPC::ChannelHandle>(),
-      &shutdown_event_, gpu_memory_buffer_manager_.get());
-  return gpu_channel_;
+void GpuService::EstablishGpuChannelOnMainThreadDone(
+    bool locked,
+    int client_id,
+    mojom::ChannelHandlePtr channel_handle,
+    mojom::GpuInfoPtr gpu_info) {
+  DCHECK(IsMainThread());
+  scoped_refptr<gpu::GpuChannelHost> gpu_channel;
+  if (client_id) {
+    // TODO(penghuang): Get the real gpu info from mus.
+    gpu_channel = gpu::GpuChannelHost::Create(
+        this, client_id, gpu::GPUInfo(),
+        channel_handle.To<IPC::ChannelHandle>(), &shutdown_event_,
+        gpu_memory_buffer_manager_.get());
+  }
+
+  auto auto_lock = base::WrapUnique<base::AutoLock>(
+      locked ? nullptr : new base::AutoLock(lock_));
+  DCHECK(is_establishing_);
+  DCHECK(!gpu_channel_);
+
+  is_establishing_ = false;
+  gpu_channel_ = gpu_channel;
+  establishing_condition_.Broadcast();
+
+  for (const auto& i : establish_callbacks_)
+    i.Run();
+  establish_callbacks_.clear();
+  gpu_service_.reset();
 }
 
 bool GpuService::IsMainThread() {