[tracing] Introduce BACKGROUND mode in MemoryInfra

This CL makes following changes:
1. Adds a BACKGROUND mode in the dump triggers in trace config.
1. Periodic dumps can be disabled on passing 0 as interval.
2. On BACKGROUND mode only whitelisted dump providers are invoked.
3. Clean up periodic dump timer set up.
4. MemoryDumpSessionState is initialized with config in the renderer
   also.

BUG=613198

Review-Url: https://codereview.chromium.org/1995573003
Cr-Commit-Position: refs/heads/master@{#396927}


CrOS-Libchrome-Original-Commit: 13ebc734eab7950938afbfac677080604d972d91
7 files changed
tree: 2f09231d3bb8f8123c1d8f715a3db46b6e7a3402
  1. base/
  2. build/
  3. components/
  4. dbus/
  5. device/
  6. ipc/
  7. mojo/
  8. testing/
  9. third_party/
  10. ui/