Add GPU.WatchdogThread.WaitTime histogram

Bug: 949839
Change-Id: Ie6a8fe29ff2adedc08910834cebe831050e14b8c
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2097247Reviewed-by: Zhenyao Mo <zmo@chromium.org>
Commit-Queue: Maggie Chen <magchen@chromium.org>
Cr-Commit-Position: refs/heads/master@{#749171}

gpu/ipc/service/gpu_watchdog_thread_v2.cc

@@ -741,6 +741,10 @@ void GpuWatchdogThreadImplV2::WatchedThreadNeedsMoreThreadTimeHistogram(
       // number to calculate the number of users who had already quit.
       RecordNumOfUsersWaitingWithExtraThreadTimeHistogram(
           count_of_more_gpu_thread_time_allowed_);
+
+      // Used by GPU.WatchdogThread.WaitTime later
+      time_in_wait_for_full_thread_time_ =
+          count_of_more_gpu_thread_time_allowed_ * watchdog_timeout_;
     }
   }
 }
@@ -761,6 +765,23 @@ void GpuWatchdogThreadImplV2::WatchedThreadGetsExtraTimeoutHistogram(
       GpuWatchdogTimeoutHistogram(GpuWatchdogTimeoutEvent::kProgressAfterWait);
       base::UmaHistogramExactLinear(
           "GPU.WatchdogThread.WaitTime.ProgressAfterWait", count, kMax);
+
+#if defined(OS_WIN)
+      // Add the time the GPU thread was given for the full thread time up to 60
+      // seconds. GPU.WatchdogThread.WaitTime is essentially equal to
+      // GPU.WatchdogThread.WaitTime.ProgressAfterWait on non-Windows systems.
+      base::TimeDelta wait_time = base::TimeDelta::FromSeconds(count);
+      wait_time += time_in_wait_for_full_thread_time_;
+
+      constexpr base::TimeDelta kMinTime = base::TimeDelta::FromSeconds(1);
+      constexpr base::TimeDelta kMaxTime = base::TimeDelta::FromSeconds(150);
+      constexpr int kBuckets = 50;
+
+      // The time the GPU main thread takes to finish a task after a "hang" is
+      // dectedted.
+      base::UmaHistogramCustomTimes("GPU.WatchdogThread.WaitTime", wait_time,
+                                    kMinTime, kMaxTime, kBuckets);
+#endif
     }
   }
 }

gpu/ipc/service/gpu_watchdog_thread_v2.h

@@ -168,6 +168,10 @@ class GPU_IPC_SERVICE_EXPORT GpuWatchdogThreadImplV2
   // continue due to not enough thread time.
   int count_of_more_gpu_thread_time_allowed_ = 0;
 
+  // The total timeout, up to 60 seconds, the watchdog thread waits for the GPU
+  // main thread to get full thread time.
+  base::TimeDelta time_in_wait_for_full_thread_time_;
+
   // After detecting GPU hang and continuing running through
   // OnGpuWatchdogTimeout for the max cycles, the GPU main thread still cannot
   // get the full thread time.