Project Eraser: Kill chrome://memory.

This deletes the majority of the code supporting chrome://memory
pages. There's still a little bit more of follow-up work to clean up
memory_details*.cc files, but those will require some changes to logic
and thus is better to do them in a separate CL.


Review URL:

Cr-Commit-Position: refs/heads/master@{#382198}
64 files changed