Reset PageHandlerInfo in glic::Host::Shutdown()

This CL resets PageHandlerInfo state on in Host::Shutdown() to
mitigate potential dangling refs.

Shutdown() resets the host `contents_` which owns the
GlicPageHandler - so any refs to the page handler must be reset
before the contents is destroyed.

Bug: 450660162
Change-Id: Ic154b174efe1df4151d90d811191479f8a9fbe82
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/7060090
Reviewed-by: Bryant Chandler <[email protected]>
Commit-Queue: Tom Lukaszewicz <[email protected]>
Cr-Commit-Position: refs/heads/main@{#1532367}

Author: Thomas Lukaszewicz

chrome/browser/glic/host/host.cc

@@ -77,6 +77,7 @@ void Host::SetDelegate(EmbedderDelegate* new_delegate) {
 }
 
 void Host::Shutdown() {
+  handler_info_.reset();
   contents_.reset();
 }
 
@@ -275,7 +276,7 @@ void Host::NotifyWindowIntentToShow() {
 }
 
 void Host::UnsetWebClient(GlicWebClientAccess* web_client) {
-  if (handler_info_ && handler_info_->web_client != web_client) {
+  if (!handler_info_ || handler_info_->web_client != web_client) {
     return;
   }