[Passwords] Remove kDeletePasswordSyncMetadataWhenNoReadable

This mitigation was added during the launch of Password Sync USS.
Since deleting all sync metadata is intrusive and unprecedented, the
feature toggle was added as safety mechanism and has always been
enabled by default.

Looking at UMA, it's safe to drop this feature. It is doing the right
thing in the rare occasion of failure in reading sync metadata.

Bug: 1126051
Change-Id: I8c19b60d30d1d1389b2ab9078ace3f5b0af078dc
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2404448Reviewed-by: Mohamed Amir Yosef <mamir@chromium.org>
Commit-Queue: Mohamed Amir Yosef <mamir@chromium.org>
Commit-Queue: Jan Wilken Dörrie <jdoerrie@chromium.org>
Auto-Submit: Jan Wilken Dörrie <jdoerrie@chromium.org>
Cr-Commit-Position: refs/heads/master@{#806163}

components/password_manager/core/browser/sync/password_sync_bridge.cc

@@ -31,12 +31,6 @@ namespace password_manager {
 
 namespace {
 
-// Controls whether we should delete the sync metadata when they aren't
-// readable.
-const base::Feature kDeletePasswordSyncMetadataWhenNoReadable{
-    "DeletePasswordSyncMetadataWhenNoReadable",
-    base::FEATURE_ENABLED_BY_DEFAULT};
-
 // Error values for reading sync metadata.
 // Used in metrics: "PasswordManager.SyncMetadataReadError". These values
 // are persisted to logs. Entries should not be renumbered and numeric values
@@ -256,17 +250,10 @@ PasswordSyncBridge::PasswordSyncBridge(
   } else {
     batch = password_store_sync_->GetMetadataStore()->GetAllSyncMetadata();
     if (!batch) {
-      if (base::FeatureList::IsEnabled(
-              kDeletePasswordSyncMetadataWhenNoReadable)) {
-        // If the metadata cannot be read, it's mostly a persistent error, and
-        // hence we should drop the metadata to go throw the initial sync flow.
-        password_store_sync_->GetMetadataStore()->DeleteAllSyncMetadata();
-        batch = std::make_unique<syncer::MetadataBatch>();
-      } else {
-        this->change_processor()->ReportError(
-            {FROM_HERE,
-             "Failed reading passwords metadata from password store."});
-      }
+      // If the metadata cannot be read, it's mostly a persistent error, and
+      // hence we should drop the metadata to go throw the initial sync flow.
+      password_store_sync_->GetMetadataStore()->DeleteAllSyncMetadata();
+      batch = std::make_unique<syncer::MetadataBatch>();
       sync_metadata_read_error = SyncMetadataReadError::kReadFailed;
     }
   }