Record the GPU watchdog arm_disarm_counter in the main thread

It is for the debugging purpose only and it wil have a performance impact.
The code will be removed immediately once valid crash dumps are collected.

Bug: 885066,885066
Change-Id: Ie8761ed4e6050a07e76af0a030b67dab5bb011e8
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2129028
Commit-Queue: Maggie Chen <magchen@chromium.org>
Reviewed-by: Zhenyao Mo <zmo@chromium.org>
Cr-Commit-Position: refs/heads/master@{#756461}

gpu/ipc/service/gpu_watchdog_thread_v2.cc

@@ -378,7 +378,12 @@ void GpuWatchdogThreadImplV2::UpdateInitializationFlag() {
 void GpuWatchdogThreadImplV2::Arm() {
   DCHECK(watched_gpu_task_runner_->BelongsToCurrentThread());
 
-  base::subtle::NoBarrier_AtomicIncrement(&arm_disarm_counter_, 1);
+  if (hits_termination_.IsSet()) {
+    base::subtle::NoBarrier_AtomicIncrement(&arm_disarm_counter_, 1);
+  } else {
+    arm_disarm_counter_main_thread_ =
+        base::subtle::NoBarrier_AtomicIncrement(&arm_disarm_counter_, 1);
+  }
 
   // Arm/Disarm are always called in sequence. Now it's an odd number.
   DCHECK(IsArmed());
@@ -387,7 +392,12 @@ void GpuWatchdogThreadImplV2::Arm() {
 void GpuWatchdogThreadImplV2::Disarm() {
   DCHECK(watched_gpu_task_runner_->BelongsToCurrentThread());
 
-  base::subtle::NoBarrier_AtomicIncrement(&arm_disarm_counter_, 1);
+  if (hits_termination_.IsSet()) {
+    base::subtle::NoBarrier_AtomicIncrement(&arm_disarm_counter_, 1);
+  } else {
+    arm_disarm_counter_main_thread_ =
+        base::subtle::NoBarrier_AtomicIncrement(&arm_disarm_counter_, 1);
+  }
 
   // Arm/Disarm are always called in sequence. Now it's an even number.
   DCHECK(!IsArmed());
@@ -397,7 +407,13 @@ void GpuWatchdogThreadImplV2::InProgress() {
   DCHECK(watched_gpu_task_runner_->BelongsToCurrentThread());
 
   // Increment by 2. This is equivalent to Disarm() + Arm().
-  base::subtle::NoBarrier_AtomicIncrement(&arm_disarm_counter_, 2);
+
+  if (hits_termination_.IsSet()) {
+    base::subtle::NoBarrier_AtomicIncrement(&arm_disarm_counter_, 2);
+  } else {
+    arm_disarm_counter_main_thread_ =
+        base::subtle::NoBarrier_AtomicIncrement(&arm_disarm_counter_, 2);
+  }
 
   // Now it's an odd number.
   DCHECK(IsArmed());
@@ -586,6 +602,10 @@ void GpuWatchdogThreadImplV2::DeliberatelyTerminateToRecoverFromHang() {
     return;
   }
 
+  // Debug only. To be deleted
+  hits_termination_.Set();
+  base::debug::Alias(&arm_disarm_counter_main_thread_);
+
 #if defined(OS_WIN)
   if (IsDebuggerPresent())
     return;

gpu/ipc/service/gpu_watchdog_thread_v2.h

@@ -227,6 +227,11 @@ class GPU_IPC_SERVICE_EXPORT GpuWatchdogThreadImplV2
   bool foregrounded_event_ = false;
   bool power_resumed_event_ = false;
 
+  // TODO (magche@): Debugging only. This has a measurable performance impact
+  // and should be removed once valid crash dumps are collected.
+  base::AtomicFlag hits_termination_;
+  base::subtle::Atomic32 arm_disarm_counter_main_thread_ = 0;
+
   // For gpu testing only.
   const bool is_test_mode_;
   // Set by the watchdog thread and Read by the test thread.