Fix 29bb707e

Compilation on GYP fails due to missing OnCriticalMemoryPressure
overload that accepts size_t parameter. In this case the compiler
complains about hiding virtual function.

This patch reintroduces the missing functions.

Bug: 
Change-Id: I493891f6908987a6f27c669a16f6c3772339333d
Reviewed-on: https://chromium-review.googlesource.com/844077Reviewed-by: Bill Budge <bbudge@chromium.org>
Commit-Queue: Ivica Bogosavljevic <ivica.bogosavljevic@mips.com>
Cr-Commit-Position: refs/heads/master@{#50306}