Disable Quick View by default and add about flag to enable it.

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 1cf9ce5d7ffe91f579ba6efbdde276681ae02c14..f66e286e492db19cf881c9594918c27509a29e5b 100644
--- a/tools/metrics/histograms/histograms.xml
+++ b/tools/metrics/histograms/histograms.xml
@@ -81176,6 +81176,7 @@ To add a new entry, add it with any value and run test to compute valid value.
   <int value="-384589459" label="disable-supervised-user-safesites"/>
   <int value="-378180863" label="disable-panels"/>
   <int value="-378033324" label="disable-win32k-renderer-lockdown"/>
+  <int value="-364325011" label="enable-files-quick-view"/>
   <int value="-362022976" label="disable-quirks-client"/>
   <int value="-360038744" label="invert-viewport-scroll-order"/>
   <int value="-351552989" label="disable-hosted-apps-in-windows"/>
@@ -81186,6 +81187,7 @@ To add a new entry, add it with any value and run test to compute valid value.
   <int value="-344343842" label="disable-experimental-app-list"/>
   <int value="-340622848" label="disable-javascript-harmony-shipping"/>
   <int value="-340255045" label="allow-nacl-socket-api"/>
+  <int value="-329727402" label="disable-files-quick-view"/>
   <int value="-328361990" label="enable-experimental-extension-apis"/>
   <int value="-322827131" label="tab-management-experiment-type-basil"/>
   <int value="-320820051" label="enable-zero-copy"/>