Add DCHECK for shared_timer_suspended_ which shouldn't be negative

content/child/blink_platform_impl.cc

Index: content/child/blink_platform_impl.cc
diff --git a/content/child/blink_platform_impl.cc b/content/child/blink_platform_impl.cc
index 2fd314fd8f2d3bcb2ed783ec154a7840d6ffad9e..724188ad4cba278b73ad6e4a4937c467ec418652 100644
--- a/content/child/blink_platform_impl.cc
+++ b/content/child/blink_platform_impl.cc
@@ -902,6 +902,8 @@ void BlinkPlatformImpl::SuspendSharedTimer() {
 }
 
 void BlinkPlatformImpl::ResumeSharedTimer() {
+  DCHECK_GT(shared_timer_suspended_, 0);
+
   // The shared timer may have fired or been adjusted while we were suspended.
   if (--shared_timer_suspended_ == 0 &&
       (!shared_timer_.IsRunning() ||