Add chrome://flags#enable-launcher-app-paging

This change adds a flag to enable the new launcher app drag redesign.
Design doc:
https://docs.google.com/document/d/1klNglz8LFuCoHQDHo43SQaBMxnvCRSDAl_BakCSpVto/edit

Bug: 996822:
Change-Id: I890a35a579b5ce83ef96d2027a0091c503391793
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2240030
Reviewed-by: Xiyuan Xia <[email protected]>
Commit-Queue: Ana Salazar <[email protected]>
Cr-Commit-Position: refs/heads/master@{#777343}
diff --git a/chrome/browser/flag_descriptions.cc b/chrome/browser/flag_descriptions.cc
index 8bf2c52..d2464c0 100644
--- a/chrome/browser/flag_descriptions.cc
+++ b/chrome/browser/flag_descriptions.cc
@@ -3551,6 +3551,11 @@
     "Enable use of high-resolution scrolling events from supported mice (those "
     "which report REL_WHEEL_HI_RES from the Linux kernel).";
 
+const char kNewDragSpecInLauncherName[] = "Enable Launcher App Paging";
+const char kNewDragSpecInLauncherDescription[] =
+    "Show visual affordance of launcher app pages and enable page previews "
+    "when dragging apps.";
+
 const char kEnableNeuralStylusPalmRejectionName[] =
     "Enable Neural Palm Detection";
 const char kEnableNeuralStylusPalmRejectionDescription[] =