Fix "--disable-hang-monitor" command line flag

Before this CL, HungRendererDialogView ("Page Unresponsive") dialog was shown even if "--disable-hang-monitor" command line flag was specified.

After this CL, the command line will work as expected. This switch is useful when you use debugger.

Bug: 1161698
Change-Id: I19089305a62e31d396cd1a69aef86a08cbc301ad
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2602957Reviewed-by: Avi Drissman <avi@chromium.org>
Reviewed-by: Kentaro Hara <haraken@chromium.org>
Reviewed-by: Kouhei Ueno <kouhei@chromium.org>
Commit-Queue: Minoru Chikamune <chikamune@chromium.org>
Cr-Commit-Position: refs/heads/master@{#839406}

content/browser/web_contents/web_contents_impl.cc

@@ -3957,6 +3957,11 @@ bool WebContentsImpl::IsJavaScriptDialogShowing() const {
 }
 
 bool WebContentsImpl::ShouldIgnoreUnresponsiveRenderer() {
+  // Suppress unresponsive renderers if the command line asks for it.
+  if (base::CommandLine::ForCurrentProcess()->HasSwitch(
+          switches::kDisableHangMonitor))
+    return true;
+
   if (suppress_unresponsive_renderer_count_ > 0)
     return true;