[Home] Allow bookmarks, downloads, and history menu items to open sheet

This change adds a finch flag "ChromeHomeMenuItemsExpandSheet" that
allows the bookmarks, downloads, and history menu items to be shown
despite Chrome Home being enabled. Selecting these items expands the
bottom sheet to half height with the selected content being shown.
The tap count will be reset if either Chrome Home or the feature is
disabled. Tap count can be configured via finch with the "max_taps"
parameter.

BUG=792573

Change-Id: Ibc66e59aa773a69c474f08e2fc7fa9c708d33468
Reviewed-on: https://chromium-review.googlesource.com/806257
Commit-Queue: Matthew Jones <[email protected]>
Reviewed-by: Theresa <[email protected]>
Reviewed-by: Ted Choc <[email protected]>
Cr-Commit-Position: refs/heads/master@{#525049}
diff --git a/chrome/browser/flag_descriptions.cc b/chrome/browser/flag_descriptions.cc
index 1f81de4..4b6e71bb 100644
--- a/chrome/browser/flag_descriptions.cc
+++ b/chrome/browser/flag_descriptions.cc
@@ -1696,6 +1696,13 @@
     "Expand bottom sheet on startup in Chrome Home after a period of"
     " inactivity.";
 
+const char kChromeHomeMenuItemsName[] =
+    "Show bookmarks, downloads, and history menu items in Chrome Home";
+const char kChromeHomeMenuItemsDescription[] =
+    "Shows bookmarks, downloads, and history menu items in the overflow menu"
+    " when Chrome Home is enabled. These items will open the bottom sheet to"
+    " show the desired content.";
+
 const char kChromeHomeOptOutSnackbarName[] = "Chrome Home Opt-out Snackbar";
 const char kChromeHomeOptOutSnackbarDescription[] =
     "Show a snackbar prompting users to take a survey the first time they"