App List: Refactor ContentsSwitcherView so it doesn't hard-code pages.

ui/app_list/views/contents_switcher_view.cc

Index: ui/app_list/views/contents_switcher_view.cc
diff --git a/ui/app_list/views/contents_switcher_view.cc b/ui/app_list/views/contents_switcher_view.cc
index 994a1fe5e44af71398c266ce9cde0d448097a50f..95669439fdb2f06df7d6ed6533d0e8d832cb101b 100644
--- a/ui/app_list/views/contents_switcher_view.cc
+++ b/ui/app_list/views/contents_switcher_view.cc
@@ -4,10 +4,8 @@
 
 #include "ui/app_list/views/contents_switcher_view.h"
 
-#include "grit/ui_resources.h"
 #include "ui/app_list/app_list_constants.h"
 #include "ui/app_list/views/contents_view.h"
-#include "ui/base/resource/resource_bundle.h"
 #include "ui/views/controls/button/custom_button.h"
 #include "ui/views/controls/button/image_button.h"
 #include "ui/views/layout/box_layout.h"
@@ -27,23 +25,17 @@ ContentsSwitcherView::ContentsSwitcherView(ContentsView* contents_view)
 
   buttons_->SetLayoutManager(new views::BoxLayout(
       views::BoxLayout::kHorizontal, 0, 0, kButtonSpacing));
-  // TODO(mgiuca): Dynamically generate these buttons from the subviews of
-  // |contents_view|.
-  AddSwitcherButton(
-      IDR_APP_LIST_SEARCH_ICON,
-      contents_view->GetPageIndexForNamedPage(ContentsView::NAMED_PAGE_START));
-  AddSwitcherButton(
-      IDR_APP_LIST_APPS_ICON,
-      contents_view->GetPageIndexForNamedPage(ContentsView::NAMED_PAGE_APPS));
 }
 
 ContentsSwitcherView::~ContentsSwitcherView() {}
 
 void ContentsSwitcherView::AddSwitcherButton(int resource_id, int page_index) {
   views::ImageButton* button = new views::ImageButton(this);
-  button->SetImage(
-      views::CustomButton::STATE_NORMAL,
-      ui::ResourceBundle::GetSharedInstance().GetImageSkiaNamed(resource_id));
+  if (resource_id) {
+    button->SetImage(
+        views::CustomButton::STATE_NORMAL,
+        ui::ResourceBundle::GetSharedInstance().GetImageSkiaNamed(resource_id));
+  }
   button->set_tag(page_index);
   buttons_->AddChildView(button);
 }