Add a flag to specify whether to show ARC Files app in launcher.

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 565f10fb81244861e350d99984f34ae311ab3303..7f458b65a2fb275a2d1dc29eaa358286c78b0729 100644
--- a/tools/metrics/histograms/histograms.xml
+++ b/tools/metrics/histograms/histograms.xml
@@ -95573,6 +95573,7 @@ value.
   <int value="-2143328006"
       label="enable-fill-on-account-select-no-highlighting"/>
   <int value="-2143113994" label="enable-ephemeral-apps-in-webstore"/>
+  <int value="-2134333982" label="ShowArcFilesApp:enabled"/>
   <int value="-2134244069" label="HttpFormWarning:enabled"/>
   <int value="-2132591642" label="enable-input-view"/>
   <int value="-2122048316"
@@ -95830,6 +95831,7 @@ value.
   <int value="-1077752943" label="enable-password-generation"/>
   <int value="-1075156797" label="enable-brotli"/>
   <int value="-1075089382" label="enable-physical-web"/>
+  <int value="-1073479583" label="ShowArcFilesApp:disabled"/>
   <int value="-1062119671" label="enable-password-force-saving"/>
   <int value="-1056310158" label="disable-memory-pressure-chromeos"/>
   <int value="-1052782474" label="enable-cloud-devices"/>