App list: TileItemView::SetAppListItem exits early if item already set.

ui/app_list/views/tile_item_view.cc

 // Copyright 2014 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "ui/app_list/views/tile_item_view.h"
 
 #include "base/strings/utf_string_conversions.h"
 #include "ui/app_list/app_list_constants.h"
 #include "ui/app_list/app_list_item.h"
 #include "ui/app_list/app_list_model.h"
@@ skipping 76 matching lines @@
   SetLayoutManager(layout_manager);
 
   icon_->SetImageSize(gfx::Size(kTileImageSize, kTileImageSize));
 
   ui::ResourceBundle& rb = ui::ResourceBundle::GetSharedInstance();
   title_->SetAutoColorReadabilityEnabled(false);
   title_->SetEnabledColor(kGridTitleColor);
   title_->SetFontList(rb.GetFontList(kItemTextFontStyle));
   title_->SetHorizontalAlignment(gfx::ALIGN_CENTER);
 
+  // When |item_| is NULL, the tile is invisible. Calling SetAppListItem with a
+  // non-NULL item makes the tile visible.
+  SetVisible(false);

[Matt Giuca, 2014/06/16 00:29:28]

I don't think adding this actually changes any behaviour (since SetAppListItem
appears to always be called as soon as this guy is created), but it's good to
have it for consistent state, as noted in the comment.

Without this, the test fails because calling SetAppListItem(NULL) will no longer
make the tile invisible. If we make the tile start out invisible, then the
early-exit behaviour in SetAppListItem(NULL) is correct.

+
   AddChildView(icon_);
   AddChildView(title_);
 }
 
 TileItemView::~TileItemView() {
 }
 
 void TileItemView::SetAppListItem(AppListItem* item) {
+  // TODO(calamity): This will not update if the contents of |item_| have
+  // changed since it was last assigned. Add an observer to refresh when the
+  // item changes.
+  if (item == item_)
+    return;
+
   item_ = item;
   if (!item) {
     SetVisible(false);
     icon_->SetImage(NULL);
     title_->SetText(base::string16());
     return;
   }
 
   SetVisible(true);
   icon_->SetImage(item_->icon());
   title_->SetText(base::UTF8ToUTF16(item_->name()));
 
   background_->set_strip_color(
       color_utils::CalculateKMeanColorOfBitmap(*item_->icon().bitmap()));
 }
 
 gfx::Size TileItemView::GetPreferredSize() const {
   return gfx::Size(kTileSize, kTileSize);
 }
 
 void TileItemView::ButtonPressed(views::Button* sender,
                                  const ui::Event& event) {
   item_->Activate(event.flags());
 }
 
 }  // namespace app_list