Create the base Custom Context Menu Dialog.

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 630dcc9c3eab85be0429371d4727c2ab88df9179..a97ffef2f66bd8e9f6262a03309f29f80ac10d92 100644
--- a/tools/metrics/histograms/histograms.xml
+++ b/tools/metrics/histograms/histograms.xml
@@ -100594,6 +100594,7 @@ from previous Chrome versions.
   <int value="379428799" label="security-chip-animation"/>
   <int value="385969127" label="disable-win32k-lockdown"/>
   <int value="387178525" label="VideoFullscreenOrientationLock:enabled"/>
+  <int value="388996324" label="CustomContextMenu:disabled"/>
   <int value="400322063" label="ash-disable-screen-orientation-lock"/>
   <int value="401983950" label="enable-spdy4"/>
   <int value="402143634" label="enable-search-button-in-omnibox-always"/>
@@ -100666,6 +100667,7 @@ from previous Chrome versions.
   <int value="646252875" label="ReadItLaterInMenu:enabled"/>
   <int value="646738320" label="disable-gesture-editing"/>
   <int value="650602639" label="enable-autofill-keyboard-accessory-view"/>
+  <int value="652561231" label="CustomContextMenu:enabled"/>
   <int value="683410401"
       label="enable-proximity-auth-bluetooth-low-energy-discovery"/>
   <int value="684806628" label="TranslateLanguageByULP:disabled"/>