Apply Chrome-specific built-in isolated origins on startup.

This CL adds the ability to apply built-in isolated origins that might
be optionally specified in the internal repo.  Note that this is still
subject to normal site isolation memory thresholds as well as flags
that disable site isolation.  The purpose of this CL is to introduce a
permanent mechanism to replace the set of origins that are currently
applied via field trials on Android using IsolateOrigins.

The internal list is currently set up to be loaded only on Android
official Chrome builds.  It can be tested on any developer builds,
including on desktop, by setting a GN flag
use_internal_isolated_origins=true.  This requires having src-internal
in your checkout (in particular, having
components/site_isolation/internal).

Other relevant (internal-only) CLs:

Adding internal isolated origins list:
https://chrome-internal-review.googlesource.com/c/chrome/components/site_isolation/+/2829993

Setting up internal repo to populate components/site_isolation/internal:
https://chrome-internal-review.googlesource.com/c/chrome/src-internal/+/2841494

Bug: 1005895
Change-Id: I22f3834ac2cecdab7a461a58c11455f6cd7f6697
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2121074
Reviewed-by: Thomas Anderson <[email protected]>
Reviewed-by: Daniel Cheng <[email protected]>
Reviewed-by: Colin Blundell <[email protected]>
Reviewed-by: Ɓukasz Anforowicz <[email protected]>
Commit-Queue: Alex Moshchuk <[email protected]>
Cr-Commit-Position: refs/heads/master@{#761528}
diff --git a/chrome/browser/DEPS b/chrome/browser/DEPS
index f0b0891..634c8e9 100644
--- a/chrome/browser/DEPS
+++ b/chrome/browser/DEPS
@@ -242,6 +242,7 @@
   "+components/sessions/core",
   "+components/signin/core/browser",
   "+components/signin/public",
+  "+components/site_isolation",
   "+components/spellcheck",
   "+components/sqlite_proto",
   "+components/ssl_errors",