GitLab

Enables browser access to platform configuration values on the render
side.

Adds the following classes:
  - CastBindings - automatically manages lifetime of a cast_shell
    binding
  - QueryableDataStore - syncs queryable data between browser process
    and renderer thread
  - QueryableData - enables querying platform configuration values
  - QueryableDataBindings - binds InterfacePtr on browser side to its
    implementation on the render side
  - QueryableDataHost - enbles sending configuration values

Classes listed above are moved from eureka internal for code cleanup
reasons.

Bug: internal b/120800068
Merge-With: eureka-internal/228719
Merge-With: eureka-internal/230875
Test: CQ
Change-Id: Id8ada0924d6b91f8781cc4508ecfca79a864bb15
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1416401
Commit-Queue: Marzena Dell'Aquila <mdellaquila@google.com>
Reviewed-by: Daniel Cheng <dcheng@chromium.org>
Reviewed-by: Sean Topping <seantopping@chromium.org>
Reviewed-by: John Abd-El-Malek <jam@chromium.org>
Reviewed-by: Luke Halliwell <halliwell@chromium.org>
Cr-Commit-Position: refs/heads/master@{#655405}