Remove expired histograms -- BookmarkManager.Num*

Remove expired histograms:
1. BookmarkManager.NumDraggedInSession
2. BookmarkManager.NumReorderButtonInSession

Bug: 1052939
Change-Id: I929b8140d89b9e351ab8c2069e416d2b0d0d3279
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2298722Reviewed-by: Theresa  <twellington@chromium.org>
Reviewed-by: Ilya Sherman <isherman@chromium.org>
Commit-Queue: Lijin Shen <lazzzis@google.com>
Cr-Commit-Position: refs/heads/master@{#788899}

chrome/android/java/src/org/chromium/chrome/browser/bookmarks/BookmarkItemsAdapter.java

@@ -16,7 +16,6 @@ import androidx.annotation.VisibleForTesting;
 import androidx.recyclerview.widget.RecyclerView;
 import androidx.recyclerview.widget.RecyclerView.ViewHolder;
 
-import org.chromium.base.metrics.RecordHistogram;
 import org.chromium.base.metrics.RecordUserAction;
 import org.chromium.chrome.R;
 import org.chromium.chrome.browser.bookmarks.BookmarkBridge.BookmarkItem;
@@ -71,10 +70,6 @@ class BookmarkItemsAdapter extends DragReorderableListAdapter<BookmarkItem>
     // Keep track of the currently highlighted bookmark - used for "show in folder" action.
     private BookmarkId mHighlightedBookmark;
 
-    // For metrics
-    private int mDragReorderCount;
-    private int mMoveButtonCount;
-
     private BookmarkModelObserver mBookmarkModelObserver = new BookmarkModelObserver() {
         @Override
         public void bookmarkNodeChanged(BookmarkItem node) {
@@ -276,7 +271,6 @@ class BookmarkItemsAdapter extends DragReorderableListAdapter<BookmarkItem>
     // BookmarkUIObserver implementations.
     @Override
     public void onDestroy() {
-        recordSessionReorderInfo(); // For metrics
         mDelegate.removeUIObserver(this);
         mDelegate.getModel().removeObserver(mBookmarkModelObserver);
         mDelegate.getSelectionDelegate().removeObserver(this);
@@ -294,7 +288,6 @@ class BookmarkItemsAdapter extends DragReorderableListAdapter<BookmarkItem>
         mCurrentFolder = folder;
 
         if (!(folder.equals(mCurrentFolder))) {
-            recordSessionReorderInfo();
             mCurrentFolder = folder;
         }
         enableDrag();
@@ -308,7 +301,6 @@ class BookmarkItemsAdapter extends DragReorderableListAdapter<BookmarkItem>
 
     @Override
     public void onSearchStateSet() {
-        recordSessionReorderInfo(); // For metrics
         clearHighlight();
         disableDrag();
         // Headers should not appear in Search mode
@@ -374,20 +366,6 @@ class BookmarkItemsAdapter extends DragReorderableListAdapter<BookmarkItem>
         populateTopLevelFoldersList();
     }
 
-    private void recordSessionReorderInfo() {
-        // Record metrics when we are exiting a folder (mCurrentFolder must not be null)
-        // Cannot reorder top level folders or partner bookmarks
-        if (mCurrentFolder != null && !topLevelFoldersShowing()
-                && mCurrentFolder.getType() != BookmarkType.PARTNER) {
-            RecordHistogram.recordCount1000Histogram(
-                    "BookmarkManager.NumDraggedInSession", mDragReorderCount);
-            RecordHistogram.recordCount1000Histogram(
-                    "BookmarkManager.NumReorderButtonInSession", mMoveButtonCount);
-            mDragReorderCount = 0;
-            mMoveButtonCount = 0;
-        }
-    }
-
     /**
      * Updates mPromoHeaderType. Makes sure that the 0th index of mElements is consistent with the
      * promo header. This 0th index is null iff there is a promo header.
@@ -490,9 +468,6 @@ class BookmarkItemsAdapter extends DragReorderableListAdapter<BookmarkItem>
         mDelegate.getModel().reorderBookmarks(mCurrentFolder, newOrder);
         if (mDragStateDelegate.getDragActive()) {
             RecordUserAction.record("MobileBookmarkManagerDragReorder");
-            mDragReorderCount++;
-        } else {
-            mMoveButtonCount++;
         }
     }
 

tools/metrics/histograms/histograms.xml

@@ -23045,6 +23045,9 @@ reviews. Googlers can read more about this at go/gwsq-gerrit.
 
 <histogram name="BookmarkManager.NumDraggedInSession" units="bookmarks"
     expires_after="M82">
+  <obsolete>
+    Removed as of July 2020.
+  </obsolete>
   <owner>jhimawan@google.com</owner>
   <owner>twellington@google.com</owner>
   <summary>
@@ -23055,6 +23058,9 @@ reviews. Googlers can read more about this at go/gwsq-gerrit.
 
 <histogram name="BookmarkManager.NumReorderButtonInSession" units="bookmarks"
     expires_after="M82">
+  <obsolete>
+    Removed as of July 2020.
+  </obsolete>
   <owner>jhimawan@google.com</owner>
   <owner>twellington@google.com</owner>
   <summary>