[MediaDeviceSalt] Enable random salts per storage key

This CL disables the use of a global salt to initialize per-storage-key salts, and uses random salts instead.

This ends the transition period to migrate existing device IDs to the
new storage backend and effectively completes the launch of storage
partitioning for media device salts.

Bug: 1410462,1462956
Change-Id: I8041c10d60e5845ff83a226e8458d14942d82d9c
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/4909537
Auto-Submit: Guido Urdaneta <guidou@chromium.org>
Reviewed-by: Elad Alon <eladalon@chromium.org>
Commit-Queue: Elad Alon <eladalon@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1204847}

diff --git a/components/media_device_salt/media_device_salt_service.cc b/components/media_device_salt/media_device_salt_service.cc
index e7c1938..05298e65b 100644
--- a/components/media_device_salt/media_device_salt_service.cc
+++ b/components/media_device_salt/media_device_salt_service.cc

@@ -27,7 +27,7 @@
              base::FEATURE_ENABLED_BY_DEFAULT);
 BASE_FEATURE(kMediaDeviceIdRandomSaltsPerStorageKey,
              "MediaDeviceIdRandomSaltsPerStorageKey",
-             base::FEATURE_DISABLED_BY_DEFAULT);
+             base::FEATURE_ENABLED_BY_DEFAULT);
 
 namespace {