Added back button when in folder view.

ui/app_list/views/search_box_view.cc

 // Copyright (c) 2012 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/search_box_view.h"
 
 #include <algorithm>
 
 #include "base/macros.h"
 #include "base/memory/ptr_util.h"
@@ skipping 164 matching lines @@
   if (is_fullscreen_app_list_enabled_) {
     google_icon_ = new views::ImageView();
     google_icon_->SetImage(gfx::CreateVectorIcon(
         kIcGoogleBlackIcon, kGoogleIconSize, kDefaultSearchboxColor));
     content_container_->AddChildView(google_icon_);
 
     search_box_->set_placeholder_text_color(kDefaultSearchboxColor);
     search_box_->set_placeholder_text_draw_flags(
         gfx::Canvas::TEXT_ALIGN_CENTER);
     search_box_->SetFontList(search_box_->GetFontList().DeriveWithSizeDelta(2));
+  }
+  back_button_ = new SearchBoxImageButton(this);
+  ui::ResourceBundle& rb = ui::ResourceBundle::GetSharedInstance();
+  back_button_->SetImage(views::ImageButton::STATE_NORMAL,
+                         rb.GetImageSkiaNamed(IDR_APP_LIST_FOLDER_BACK_NORMAL));
+  back_button_->SetImageAlignment(views::ImageButton::ALIGN_CENTER,
+                                  views::ImageButton::ALIGN_MIDDLE);
+  SetBackButtonLabel(false);
+
+  if (is_fullscreen_app_list_enabled_) {
+    content_container_->AddChildView(google_icon_);

[vadimt, 2017/06/22 18:28:08]

Google icon is supposed to be owned by view hierarchy, but you may never add it
to the hierarchy, so it will be leaked?

Please run with ASAN to confirm the leak, then consider unique_ptr +
set_owned_by_client().

[newcomer, 2017/06/23 23:28:08]

I took xiyuan@'s suggestion of setting the visibility of the views. 

   } else {
-    back_button_ = new SearchBoxImageButton(this);
-    ui::ResourceBundle& rb = ui::ResourceBundle::GetSharedInstance();
-    back_button_->SetImage(
-        views::ImageButton::STATE_NORMAL,
-        rb.GetImageSkiaNamed(IDR_APP_LIST_FOLDER_BACK_NORMAL));
-    back_button_->SetImageAlignment(views::ImageButton::ALIGN_CENTER,
-                                    views::ImageButton::ALIGN_MIDDLE);
-    SetBackButtonLabel(false);
     content_container_->AddChildView(back_button_);
-
     search_box_->set_placeholder_text_color(kHintTextColor);
   }
   content_container_->AddChildView(search_box_);
   layout->SetFlexForView(search_box_, 1);
 
   view_delegate_->GetSpeechUI()->AddObserver(this);
   ModelChanged();
 }
 
 SearchBoxView::~SearchBoxView() {
@@ skipping 119 matching lines @@
   if (!back_button_)
     return;
 
   base::string16 back_button_label(l10n_util::GetStringUTF16(
       folder ? IDS_APP_LIST_FOLDER_CLOSE_FOLDER_ACCESSIBILE_NAME
              : IDS_APP_LIST_BACK));
   back_button_->SetAccessibleName(back_button_label);
   back_button_->SetTooltipText(back_button_label);
 }
 
+void SearchBoxView::ShowBackOrGoogleIcon(bool show_back_button) {
+  if (!is_fullscreen_app_list_enabled_)
+    return;
+
+  if (show_back_button) {
+    content_container_->AddChildViewAt(
+        back_button_, content_container_->GetIndexOf(google_icon_));
+    content_container_->RemoveChildView(google_icon_);
+  } else {
+    content_container_->AddChildViewAt(
+        google_icon_, content_container_->GetIndexOf(back_button_));
+    content_container_->RemoveChildView(back_button_);

[xiyuan, 2017/06/22 17:33:24]

The current code assumes |google_icon_| and |back_button_| are owned by the
views hierarchy. Remove them from the hierachy leaves them unowned and could
result in a memory leak.

Can we manipulate visibility instead? If we want to do the add/remove trick, we
need to make SearchBoxView owns the two.

[newcomer, 2017/06/23 23:28:08]

I set the visibility as that makes more sense to me.

+  }
+  content_container_->Layout();
+}
+
 bool SearchBoxView::OnMouseWheel(const ui::MouseWheelEvent& event) {
   if (contents_view_)
     return contents_view_->OnMouseWheel(event);
 
   return false;
 }
 
 void SearchBoxView::OnEnabledChanged() {
   search_box_->SetEnabled(enabled());
   if (speech_button_)
@@ skipping 144 matching lines @@
   NotifyQueryChanged();
 }
 
 void SearchBoxView::OnSpeechRecognitionStateChanged(
     SpeechRecognitionState new_state) {
   SpeechRecognitionButtonPropChanged();
   SchedulePaint();
 }
 
 }  // namespace app_list