Plumb base::Feature field trial association to renderers.

This CL makes the FeatureList command-line initialization code
support an optional FieldTrial name for each feature that will
be associated with the feature override when specified. Also
changes the code that generates this command-line to also
include this name.

With this change, renderers will be launched with this
association specified on the command-line, so that querying
a Feature in the renderer only that's associated with a field
trial will result in that trial being activated (and sync'd with
the browser process by the existing mechanism).

Depends on:
https://codereview.chromium.org/1471693007

BUG=561077

Review URL: https://codereview.chromium.org/1484483002

Cr-Commit-Position: refs/heads/master@{#362343}


CrOS-Libchrome-Original-Commit: b2e44d8215dd9d4ed6316c6696b576cf77cb363c
3 files changed
tree: 5f79866191d593cc7a7291533dac9ca14d84df7d
  1. base/
  2. build/
  3. components/
  4. dbus/
  5. device/
  6. ipc/
  7. mojo/
  8. testing/
  9. third_party/
  10. ui/