[Sync] Fix metadata with tracked unsyncable bookmark node.

This patch introduces check for unsyncable nodes while loading metadata
from the disk and throws away metadata if unsyncable node is tracked.

Bug: 1093024
Change-Id: Ib07c8999670b5831a3955d26734bf6704eb6232b
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2238826
Commit-Queue: Rushan Suleymanov <rushans@google.com>
Reviewed-by: Mikel Astiz <mastiz@chromium.org>
Cr-Commit-Position: refs/heads/master@{#776907}

components/sync_bookmarks/synced_bookmark_tracker.cc

@@ -608,6 +608,9 @@ SyncedBookmarkTracker::InitEntitiesFromModelAndMetadata(
   while (iterator.has_next()) {
     const bookmarks::BookmarkNode* node = iterator.Next();
     if (!model->client()->CanSyncNode(node)) {
+      if (bookmark_node_to_entities_map_.count(node) != 0) {
+        return CorruptionReason::TRACKED_MANAGED_NODE;
+      }
       continue;
     }
     if (bookmark_node_to_entities_map_.count(node) == 0) {

components/sync_bookmarks/synced_bookmark_tracker.h

@@ -297,7 +297,9 @@ class SyncedBookmarkTracker {
     UNTRACKED_BOOKMARK = 8,
     BOOKMARK_GUID_MISMATCH = 9,
     DUPLICATED_CLIENT_TAG_HASH = 10,
-    kMaxValue = DUPLICATED_CLIENT_TAG_HASH
+    TRACKED_MANAGED_NODE = 11,
+
+    kMaxValue = TRACKED_MANAGED_NODE
   };
 
   SyncedBookmarkTracker(sync_pb::ModelTypeState model_type_state,

components/sync_bookmarks/synced_bookmark_tracker_unittest.cc

@@ -47,7 +47,9 @@ enum class ExpectedCorruptionReason {
   UNTRACKED_BOOKMARK = 8,
   BOOKMARK_GUID_MISMATCH = 9,
   DUPLICATED_CLIENT_TAG_HASH = 10,
-  kMaxValue = DUPLICATED_CLIENT_TAG_HASH
+  TRACKED_MANAGED_NODE = 11,
+
+  kMaxValue = TRACKED_MANAGED_NODE
 };
 
 sync_pb::EntitySpecifics GenerateSpecifics(const std::string& title,
@@ -743,6 +745,41 @@ TEST(SyncedBookmarkTrackerTest,
       /*count=*/1);
 }
 
+TEST(SyncedBookmarkTrackerTest,
+     ShouldNotMatchModelAndMetadataIfUnsyncableNodeIsTracked) {
+  // Add a managed node with an arbitrary id 100.
+  const int64_t kManagedNodeId = 100;
+  auto owned_managed_node = std::make_unique<bookmarks::BookmarkPermanentNode>(
+      kManagedNodeId, bookmarks::BookmarkNode::FOLDER);
+  auto client = std::make_unique<bookmarks::TestBookmarkClient>();
+  bookmarks::BookmarkNode* managed_node = client->EnableManagedNode();
+
+  std::unique_ptr<bookmarks::BookmarkModel> model =
+      bookmarks::TestBookmarkClient::CreateModelWithClient(std::move(client));
+
+  // The model should contain the managed node now.
+  ASSERT_THAT(GetBookmarkNodeByID(model.get(), kManagedNodeId),
+              Eq(managed_node));
+
+  // Add entries for all the permanent nodes. TestBookmarkClient creates all the
+  // 3 permanent nodes.
+  sync_pb::BookmarkModelMetadata model_metadata =
+      CreateMetadataForPermanentNodes(model.get());
+
+  // Add unsyncable node to metadata.
+  *model_metadata.add_bookmarks_metadata() =
+      CreateNodeMetadata(managed_node->id(),
+                         /*server_id=*/"server_id");
+
+  base::HistogramTester histogram_tester;
+  EXPECT_THAT(SyncedBookmarkTracker::CreateFromBookmarkModelAndMetadata(
+                  model.get(), std::move(model_metadata)),
+              IsNull());
+  histogram_tester.ExpectUniqueSample(
+      "Sync.BookmarksModelMetadataCorruptionReason",
+      /*sample=*/ExpectedCorruptionReason::TRACKED_MANAGED_NODE, /*count=*/1);
+}
+
 TEST(SyncedBookmarkTrackerTest,
      ShouldMatchModelAndMetadataDespiteGuidMismatch) {
   base::test::ScopedFeatureList override_features;

tools/metrics/histograms/enums.xml

@@ -66180,6 +66180,7 @@ would be helpful to identify which type is being sent.
   <int value="8" label="Bookmark in model is missing sync metadata"/>
   <int value="9" label="Client tag hash does not match bookmark GUID"/>
   <int value="10" label="Duplicate client tag hashes exist"/>
+  <int value="11" label="Managed bookmark has sync metadata"/>
 </enum>
 
 <enum name="SyncBookmarkModelSyncState">