Fixed IPC memory leak of prerender alias urls messages.

This patch fixes minor leak of prerender IPC messages that are
broadcasted to all renderers to inform that alias url is added or
removed. Added check that target renderer is initialized and not dead.
More details for reasons of leaks are described in
https://bugs.chromium.org/p/chromium/issues/detail?id=813045

Bug: 813045
Change-Id: Ida6ea0eae4fbfd0e89ede9863449168d95d93fd2
Reviewed-on: https://chromium-review.googlesource.com/c/1406629
Reviewed-by: Erik Chen <erikchen@chromium.org>
Reviewed-by: Matthew Cary <mattcary@chromium.org>
Reviewed-by: Alexander Semashko <ahest@yandex-team.ru>
Commit-Queue: Alexander Yashkin <a-v-y@yandex-team.ru>
Cr-Commit-Position: refs/heads/master@{#623196}
1 file changed