Partial revert of "Added metrics to count the number of items in the shelf."

Collecting the metrics was sometimes causing a crash and has been removed
until the root cause is found.
This is only a partial revert because items are not to be removed from
tools/metrics/histograms/histograms.xml.

BUG=474702

Review URL: https://codereview.chromium.org/1070693002

Cr-Commit-Position: refs/heads/master@{#324226}

ash/metrics/user_metrics_recorder.cc

@@ -4,10 +4,7 @@
 
 #include "ash/metrics/user_metrics_recorder.h"
 
-#include "ash/shelf/shelf_delegate.h"
-#include "ash/shelf/shelf_item_types.h"
 #include "ash/shelf/shelf_layout_manager.h"
-#include "ash/shelf/shelf_model.h"
 #include "ash/shelf/shelf_view.h"
 #include "ash/shelf/shelf_widget.h"
 #include "ash/shell.h"
@@ -124,29 +121,6 @@ int GetNumVisibleWindowsInPrimaryDisplay() {
   return visible_window_count;
 }
 
-void RecordShelfItemCounts() {
-  ShelfDelegate* shelf_delegate = Shell::GetInstance()->GetShelfDelegate();
-  int pinned_item_count = 0;
-  int unpinned_item_count = 0;
-
-  for (const ShelfItem& shelf_item :
-       Shell::GetInstance()->shelf_model()->items()) {
-    if (shelf_item.type != TYPE_APP_LIST) {
-      if (shelf_delegate->IsAppPinned(
-              shelf_delegate->GetAppIDForShelfID(shelf_item.id)))
-        ++pinned_item_count;
-      else
-        ++unpinned_item_count;
-    }
-  }
-
-  UMA_HISTOGRAM_COUNTS_100("Ash.Shelf.NumberOfItems",
-                           pinned_item_count + unpinned_item_count);
-  UMA_HISTOGRAM_COUNTS_100("Ash.Shelf.NumberOfPinnedItems", pinned_item_count);
-  UMA_HISTOGRAM_COUNTS_100("Ash.Shelf.NumberOfUnpinnedItems",
-                           unpinned_item_count);
-}
-
 }  // namespace
 
 UserMetricsRecorder::UserMetricsRecorder() {
@@ -561,8 +535,6 @@ void UserMetricsRecorder::RecordPeriodicMetrics() {
   UMA_HISTOGRAM_ENUMERATION("Ash.ActiveWindowShowTypeOverTime",
                             GetActiveWindowState(),
                             ACTIVE_WINDOW_STATE_TYPE_COUNT);
-
-  RecordShelfItemCounts();
 }
 
 }  // namespace ash