cocoa: add experimental tabstrip keyboard focus support

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 a4e22d5aef91ab5bedaff14b7d6ac05249db0097..f8467d8fbdc6ce4311a09d4ac75368823897d8da 100644
--- a/tools/metrics/histograms/histograms.xml
+++ b/tools/metrics/histograms/histograms.xml
@@ -98849,6 +98849,7 @@ from previous Chrome versions.
   <int value="-2099035488" label="enable-data-reduction-proxy-bypass-warning"/>
   <int value="-2098610409" label="disable-lcd-text"/>
   <int value="-2097515669" label="disable-cast"/>
+  <int value="-2091404586" label="TabStripKeyboardFocus:enabled"/>
   <int value="-2090484194" label="ContextualSearchUrlActions:disabled"/>
   <int value="-2083195884" label="enable-firewall-hole-punching"/>
   <int value="-2082042818"
@@ -98882,6 +98883,7 @@ from previous Chrome versions.
       label="enable-search-button-in-omnibox-for-str-or-iip"/>
   <int value="-1999892428" label="force-ui-direction"/>
   <int value="-1998927516" label="enable-md-settings"/>
+  <int value="-1989747818" label="TabStripKeyboardFocus:disabled"/>
   <int value="-1985025593" label="file-manager-enable-new-gallery"/>
   <int value="-1980328793" label="trace-upload-url"/>
   <int value="-1972383451" label="disable-pinch"/>