There's an effort underway to trim down components
(https://bugs.chromium.org/p/chromium/issues/detail?id=624590).

As part of this effort, we're moving the page_load_metrics component
to chrome/.

This change moves code out of components like so:
components/page_load_metrics/browser -> chrome/browser/page_load_metrics
components/page_load_metrics/renderer -> chrome/renderer/page_load_metrics
components/page_load_metrics/common -> chrome/common/page_load_metrics

This change does not include any logic changes - it just moves code
to its new home, updates includes and build dependencies, etc.

BUG=630837

Review-Url: https://codereview.chromium.org/2177743002
Cr-Commit-Position: refs/heads/master@{#407966}