Add flags for permission prompt experiments.

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 698e1d77fed3babe8775d70b623cd34c9a999042..3590af4dbbaa678cd6db79ce066b1667f3dcbb1d 100644
--- a/tools/metrics/histograms/histograms.xml
+++ b/tools/metrics/histograms/histograms.xml
@@ -89831,6 +89831,8 @@ value.
       label="enable-fill-on-account-select-no-highlighting"/>
   <int value="-2143113994" label="enable-ephemeral-apps-in-webstore"/>
   <int value="-2132591642" label="enable-input-view"/>
+  <int value="-2122048316"
+      label="DisplayPersistenceToggleInPermissionPrompts:enabled"/>
   <int value="-2119827860" label="ash-disable-maximize-mode-window-backdrop"/>
   <int value="-2119530966" label="enable-webrtc-dtls12"/>
   <int value="-2119493239" label="enable-app-info-dialog-mac"/>
@@ -89958,12 +89960,15 @@ value.
   <int value="-1596559650" label="max-tiles-for-interest-area"/>
   <int value="-1586642651" label="MaterialDesignExtensions:disabled"/>
   <int value="-1583728573" label="AutofillCreditCardSigninPromo:disabled"/>
+  <int value="-1581724231" label="ModalPermissionPrompts:enabled"/>
   <int value="-1578295753" label="UserMediaScreenCapturing:disabled"/>
   <int value="-1572010356" label="enable-privet-v3"/>
   <int value="-1571841513" label="enable-devtools-experiments"/>
   <int value="-1559789642" label="RunAllFlashInAllowMode:enabled"/>
   <int value="-1553477903" label="ash-disable-text-filtering-in-overview-mode"/>
   <int value="-1546903171" label="enable-touch-drag-drop"/>
+  <int value="-1543316040"
+      label="DisplayPersistenceToggleInPermissionPrompts:disabled"/>
   <int value="-1536293422" label="SharedArrayBuffer:enabled"/>
   <int value="-1536242739" label="security-chip"/>
   <int value="-1514943439" label="ash-enable-swipe-to-close-in-overview-mode"/>
@@ -90115,6 +90120,7 @@ value.
   <int value="-842438090" label="enable-md-feedback"/>
   <int value="-836123854" label="wallet-service-use-sandbox"/>
   <int value="-835672415" label="PointerEventV1SpecCapturing:disabled"/>
+  <int value="-834661509" label="ModalPermissionPrompts:disabled"/>
   <int value="-825942229" label="tab-management-experiment-type-elderberry"/>
   <int value="-823165021" label="MaterialDesignUserMenu:enabled"/>
   <int value="-820041355" label="enable-transition-compositing"/>