[Android] Add uncategorized bookmark querying JNI bridge function.

In the new enhanced bookmark UI, Uncategorized items are bookmarks
under mobile and others node.

BUG=386785

Review URL: https://codereview.chromium.org/533363002

Cr-Commit-Position: refs/heads/master@{#293336}

chrome/android/java/src/org/chromium/chrome/browser/BookmarksBridge.java

@@ -203,6 +203,17 @@ public class BookmarksBridge {
         return result;
     }
 
+    /**
+     * @return The uncategorized bookmark IDs. They are direct descendant bookmarks of mobile and
+     *         other folders.
+     */
+    public List<BookmarkId> getUncategorizedBookmarkIDs() {
+        assert mIsNativeBookmarkModelLoaded;
+        List<BookmarkId> result = new ArrayList<BookmarkId>();
+        nativeGetUncategorizedBookmarkIDs(mNativeBookmarksBridge, result);
+        return result;
+    }
+
     /**
      * Reads sub-folder IDs, sub-bookmark IDs, or both of the given folder.
      *
@@ -442,6 +453,8 @@ public class BookmarksBridge {
             List<BookmarkId> bookmarksList);
     private native void nativeGetTopLevelFolderIDs(long nativeBookmarksBridge, boolean getSpecial,
             boolean getNormal, List<BookmarkId> bookmarksList);
+    private native void nativeGetUncategorizedBookmarkIDs(long nativeBookmarksBridge,
+            List<BookmarkId> bookmarksList);
     private native void nativeGetChildIDs(long nativeBookmarksBridge, long id, int type,
             boolean getFolders, boolean getBookmarks, List<BookmarkId> bookmarksList);
     private native void nativeGetAllBookmarkIDsOrderedByCreationDate(long nativeBookmarksBridge,

chrome/browser/android/bookmarks/bookmarks_bridge.cc

@@ -245,6 +245,32 @@ void BookmarksBridge::GetTopLevelFolderIDs(JNIEnv* env,
   }
 }
 
+void BookmarksBridge::GetUncategorizedBookmarkIDs(JNIEnv* env,
+                                                  jobject obj,
+                                                  jobject j_result_obj) {
+  const BookmarkNode* mobile_node = bookmark_model_->mobile_node();
+  for (int i = 0; i < mobile_node->child_count(); ++i) {
+    const BookmarkNode* node = mobile_node->GetChild(i);
+    if (!node->is_folder()) {
+      Java_BookmarksBridge_addToBookmarkIdList(env,
+                                               j_result_obj,
+                                               node->id(),
+                                               GetBookmarkType(node));
+    }
+  }
+
+  const BookmarkNode* other_node = bookmark_model_->other_node();
+  for (int i = 0; i < other_node->child_count(); ++i) {
+    const BookmarkNode* node = other_node->GetChild(i);
+    if (!node->is_folder()) {
+      Java_BookmarksBridge_addToBookmarkIdList(env,
+                                               j_result_obj,
+                                               node->id(),
+                                               GetBookmarkType(node));
+    }
+  }
+}
+
 void BookmarksBridge::GetChildIDs(JNIEnv* env,
                                   jobject obj,
                                   jlong id,

chrome/browser/android/bookmarks/bookmarks_bridge.h

@@ -49,6 +49,10 @@ class BookmarksBridge : public BaseBookmarkModelObserver,
                             jboolean get_normal,
                             jobject j_result_obj);
 
+  void GetUncategorizedBookmarkIDs(JNIEnv* env,
+                                   jobject obj,
+                                   jobject j_result_obj);
+
   void GetChildIDs(JNIEnv* env,
                    jobject obj,
                    jlong id,