ash: expose shelf auto hide functionality to private autotest JS

This CL allows calling shelf's SetAutoHideBehavior and GetAutoHideBehavior
from private autotest JavaScript API.
Calls to Ash are  being done via Mojo.

This is needed for some integration tests, in particular ARC++ Tast
test.

No logic is added/removed.

Misc: add missing #include<> reported by `git cl lint`

TEST=browser_tests --gtest_filter=AutotestPrivateApiTest.AutotestPrivate
     Tested manually from Tast test (WIP) on Nocturne
BUG=chromium:939441

Change-Id: I3b878f08c6ef8979f984d0b1e0ddd2e7075cbcd6
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1509358
Reviewed-by: Dominick Ng <[email protected]>
Reviewed-by: Steven Bennetts <[email protected]>
Reviewed-by: Stefan Kuhne <[email protected]>
Commit-Queue: Dominick Ng <[email protected]>
Auto-Submit: Ricardo Quesada <[email protected]>
Cr-Commit-Position: refs/heads/master@{#639294}
diff --git a/extensions/browser/extension_function_histogram_value.h b/extensions/browser/extension_function_histogram_value.h
index 21c3096..d4432f8 100644
--- a/extensions/browser/extension_function_histogram_value.h
+++ b/extensions/browser/extension_function_histogram_value.h
@@ -1384,6 +1384,8 @@
   AUTOTESTPRIVATE_GETARCSTATE = 1321,
   AUTOTESTPRIVATE_ISTABLETMODEENABLED = 1322,
   AUTOTESTPRIVATE_SETTABLETMODEENABLED = 1323,
+  AUTOTESTPRIVATE_GETSHELFAUTOHIDEBEHAVIOR = 1324,
+  AUTOTESTPRIVATE_SETSHELFAUTOHIDEBEHAVIOR = 1325,
   // Last entry: Add new entries above, then run:
   // python tools/metrics/histograms/update_extension_histograms.py
   ENUM_BOUNDARY