Arm the GPU watchdog during GPU process shutdown.

The GPU process is now armed to detect hangs during shutdown. This also fixes
a problem that ReportProgress() is called without Arm() first and a DCHECK is
triggered due to the wrong Arm/InProgress/Disarm order. Calling Arm() when the
GPU starts to shut down fix this order issue.

Bug:949839, 674475

Change-Id: I5f8ec78787945a09ad6cf519506175386e24a646
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1775214
Commit-Queue: Maggie Chen <magchen@chromium.org>
Reviewed-by: Zhenyao Mo <zmo@chromium.org>
Cr-Commit-Position: refs/heads/master@{#691945}

components/viz/service/gl/gpu_service_impl.cc

@@ -220,6 +220,9 @@ GpuServiceImpl::~GpuServiceImpl() {
     wait.Wait();
   }
 
+  if (watchdog_thread_)
+    watchdog_thread_->OnGpuProcessTearDown();
+
   media_gpu_channel_manager_.reset();
   gpu_channel_manager_.reset();
 

components/viz/service/gl/gpu_service_impl.h

@@ -281,6 +281,8 @@ class VIZ_SERVICE_EXPORT GpuServiceImpl : public gpu::GpuChannelManagerDelegate,
   scoped_refptr<base::SingleThreadTaskRunner> main_runner_;
   scoped_refptr<base::SingleThreadTaskRunner> io_runner_;
 
+  // Do not change the class member order here. watchdog_thread_ should be the
+  // last one to be destroyed before main_runner_ and io_runner_.
   std::unique_ptr<gpu::GpuWatchdogThread> watchdog_thread_;
 
   const gpu::GpuPreferences gpu_preferences_;

gpu/ipc/service/gpu_watchdog_thread.h

@@ -59,6 +59,11 @@ class GPU_IPC_SERVICE_EXPORT GpuWatchdogThread : public base::Thread,
   // once init is complete, before executing tasks.
   virtual void OnInitComplete() = 0;
 
+  // Notifies the watchdog when the GPU child process is being destroyed.
+  // This function is called directly from
+  // viz::GpuServiceImpl::~GpuServiceImpl()
+  virtual void OnGpuProcessTearDown() = 0;
+
   virtual void GpuWatchdogHistogram(GpuWatchdogThreadEvent thread_event) = 0;
 
   // For gpu testing only. Return status for the watchdog tests
@@ -86,6 +91,7 @@ class GPU_IPC_SERVICE_EXPORT GpuWatchdogThreadImplV1
   void OnBackgrounded() override;
   void OnForegrounded() override;
   void OnInitComplete() override {}
+  void OnGpuProcessTearDown() override {}
   void GpuWatchdogHistogram(GpuWatchdogThreadEvent thread_event) override;
   bool IsGpuHangDetectedForTesting() override;
 

gpu/ipc/service/gpu_watchdog_thread_v2.cc

@@ -86,12 +86,22 @@ void GpuWatchdogThreadImplV2::OnForegrounded() {
                      base::Unretained(this)));
 }
 
-// Called from the gpu thread when gpu init has completed
+// Called from the gpu thread when gpu init has completed.
 void GpuWatchdogThreadImplV2::OnInitComplete() {
   DCHECK(watched_gpu_task_runner_->BelongsToCurrentThread());
   Disarm();
 }
 
+// Called from the gpu thread in viz::GpuServiceImpl::~GpuServiceImpl().
+// After this, no Disarm() will be called before the watchdog thread is
+// destroyed. If this destruction takes too long, the watchdog timeout
+// will be triggered.
+void GpuWatchdogThreadImplV2::OnGpuProcessTearDown() {
+  DCHECK(watched_gpu_task_runner_->BelongsToCurrentThread());
+
+  Arm();
+}
+
 // Running on the watchdog thread.
 // On Linux, Init() will be called twice for Sandbox Initialization. The
 // watchdog is stopped and then restarted in StartSandboxLinux(). Everything
@@ -200,6 +210,9 @@ void GpuWatchdogThreadImplV2::RestartWatchdogTimeoutTask() {
   }
 }
 
+// Called from the gpu main thread.
+// The watchdog is armed only in these three functions -
+// GpuWatchdogThreadImplV2(), WillProcessTask(), and OnGpuProcessTearDown()
 void GpuWatchdogThreadImplV2::Arm() {
   DCHECK(watched_gpu_task_runner_->BelongsToCurrentThread());
 

gpu/ipc/service/gpu_watchdog_thread_v2.h

@@ -26,6 +26,7 @@ class GPU_IPC_SERVICE_EXPORT GpuWatchdogThreadImplV2
   void OnBackgrounded() override;
   void OnForegrounded() override;
   void OnInitComplete() override;
+  void OnGpuProcessTearDown() override;
   void GpuWatchdogHistogram(GpuWatchdogThreadEvent thread_event) override;
   bool IsGpuHangDetectedForTesting() override;
   void WaitForPowerObserverAddedForTesting() override;