Record the time duration for establishing proxy connection

tools/metrics/histograms/histograms.xml

Index: tools/metrics/histograms/histograms.xml
diff --git a/tools/metrics/histograms/histograms.xml b/tools/metrics/histograms/histograms.xml
index 9dab252cb5b8ab5b8fb5b5d8f885396e16afd2c8..acc5678860ef8d49dd73d8499ea053b8f0b6a5d2 100644
--- a/tools/metrics/histograms/histograms.xml
+++ b/tools/metrics/histograms/histograms.xml
@@ -34488,6 +34488,11 @@ http://cs/file:chrome/histograms.xml - but prefer this file for new entries.
   </summary>
 </histogram>
 
+<histogram name="Net.Proxy.ConnectLatency" units="ms">
+  <owner>tbansal@chromium.org</owner>
+  <summary>Time taken to establish the connection to the proxy.</summary>
+</histogram>
+
 <histogram name="Net.ProxyAuthRequested.HasConnection">
   <owner>rch@chromium.org</owner>
   <summary>
@@ -119200,6 +119205,21 @@ from previous Chrome versions.
   <affected-histogram name="Net.RequestTime2.Success"/>
 </histogram_suffixes>
 
+<histogram_suffixes name="NetProxyConnectLatencySecure" separator=".">
+  <owner>tbansal@chromium.org</owner>
+  <suffix name="Insecure" label="Insecure proxy"/>
+  <suffix name="Secure" label="Secure proxy"/>
+  <affected-histogram name="Net.Proxy.ConnectLatency"/>
+</histogram_suffixes>
+
+<histogram_suffixes name="NetProxyConnectLatencySuccess" separator=".">
+  <owner>tbansal@chromium.org</owner>
+  <suffix name="Success" label="Connection to proxy was successful"/>
+  <suffix name="TimedOut" label="Connection to proxy timed out"/>
+  <affected-histogram name="Net.Proxy.ConnectLatency.Insecure"/>
+  <affected-histogram name="Net.Proxy.ConnectLatency.Secure"/>
+</histogram_suffixes>
+
 <histogram_suffixes name="NetProxyResolverExecutionTime">
   <suffix name="UrlOver2K" label="URL length was over 2K"/>
   <suffix name="UrlOver4K" label="URL length was over 4K"/>