Remove blink_memory_mobile benchmark

We need to migrate pagesets to WprGo but I don't think
blink_memory_mobile is worth updating because it tracks almost the same
metrics as system_health benchmarks do. This benchmark should be
superseded by system_health.memory_mobile.

BUG=730036

Change-Id: Ic6877c733efce8ffd42cb3d570fb8ec55456d7b7
Reviewed-on: https://chromium-review.googlesource.com/595347
Reviewed-by: Takashi Sakamoto <[email protected]>
Reviewed-by: Kentaro Hara <[email protected]>
Reviewed-by: Helen Li <[email protected]>
Reviewed-by: Ned Nguyen <[email protected]>
Commit-Queue: Ned Nguyen <[email protected]>
Cr-Commit-Position: refs/heads/master@{#491084}
7 files changed