Add a metric to check how often SiteInstances can reuse processes

content/browser/renderer_host/render_process_host_impl.cc

Index: content/browser/renderer_host/render_process_host_impl.cc
diff --git a/content/browser/renderer_host/render_process_host_impl.cc b/content/browser/renderer_host/render_process_host_impl.cc
index e26d27268380eb4b5c3bdcbbf32032083c1372ad..67c880e1817584866f580ade9cd40bdf66da7a2c 100644
--- a/content/browser/renderer_host/render_process_host_impl.cc
+++ b/content/browser/renderer_host/render_process_host_impl.cc
@@ -3079,6 +3079,8 @@ RenderProcessHost* RenderProcessHostImpl::GetProcessHostForSiteInstance(
     case SiteInstanceImpl::ProcessReusePolicy::REUSE_PENDING_OR_COMMITTED_SITE:
       render_process_host =
           FindReusableProcessHostForSite(browser_context, site_url);
+      UMA_HISTOGRAM_BOOLEAN("SiteInstance.ReusePendingOrComittedSiteCouldReuse",

[Charlie Reis, 2017/06/07 20:15:33]

typo: Committed

[clamy, 2017/06/13 15:04:47]

Done.

+                            render_process_host != nullptr);
       break;
     default:
       break;