Renamespace symbols in third_party/absl/time/time.h and third_party/absl/time/clock.h from `base` to `absl`.
Renamespace symbols in third_party/absl/time/time.h and
third_party/absl/time/clock.h from `base` to `absl`.

LSC doc: go/lsc-absl-gplc.

Tested:
    TAP sample presubmit queue
    http://test/OCL:185694001:BASE:185694166:1518627675307:e614761b

-------------
Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=186012329

GoogleCloudPlatform/cloud-debug-java,GoogleCloudPlatform/cloud-debug-java,GoogleCloudPlatform/cloud-debug-java,GoogleCloudPlatform/cloud-debug-java