Add runhooks to multi_repo_trybots

site/dev/chrome/multi_repo_trybots.md

Index: site/dev/chrome/multi_repo_trybots.md
diff --git a/site/dev/chrome/multi_repo_trybots.md b/site/dev/chrome/multi_repo_trybots.md
index 16502ef5d3feca95b6480e8a4e96d46931df944c..c58ae2f523b115384133e72fee10c25a881ff641 100644
--- a/site/dev/chrome/multi_repo_trybots.md
+++ b/site/dev/chrome/multi_repo_trybots.md
@@ -45,6 +45,14 @@ has the form 'issue\<issue>_\<patchset>.diff'.
 An example of this being used can be seen at
 https://crrev.com/1877673002/#ps120001 .
 
+Finally, run the post-sync hooks again to update the Skia source code
+
+      $ gclient runhooks
+
+Note that if your local skia patch in `third_party/skia` isn't clean (e.g., you
+already applied some patch to it), then `gclient runhooks` won't successfully
+run. In that case, run `git reset --hard` inside `third_party/skia` before
+`gclient runhooks`.
 
 External changes not in rietveld
 --------------------------------
@@ -75,4 +83,4 @@ Try the patch
 -------------
 After committing these \<chromium>/src/DEPS and \<chromium>/src/patch/ changes
 locally, 'git cl upload' can be used in the usual way. Be sure to add
-'COMMIT=false' to the issue description to avoid accidentally checking it in.
+'COMMIT=false' to the issue description to avoid accidentally checking it in.