Use std::unique_ptr in suggestion_view and suggestion_window_view

Also add comment in "suggestion_window_controller_impl.cc"to affirm
there is no memory leak.

Bug: 1060965
Change-Id: Iccb3f2935c1cbdec31c4a260d46a6646c3975edb
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2134029Reviewed-by: Darren Shen <shend@chromium.org>
Reviewed-by: Keith Lee <keithlee@chromium.org>
Commit-Queue: My Nguyen <myy@chromium.org>
Cr-Commit-Position: refs/heads/master@{#756569}

chrome/browser/chromeos/input_method/suggestion_window_controller_impl.cc

@@ -41,6 +41,7 @@ void SuggestionWindowControllerImpl::Init() {
       active_window ? active_window->GetRootWindow()
                     : ash::Shell::GetRootWindowForNewWindows(),
       ash::kShellWindowId_VirtualKeyboardContainer);
+  // suggestion_window_view_ is deleted by DialogDelegateView::DeleteDelegate.
   suggestion_window_view_ = new ui::ime::SuggestionWindowView(
       parent, ash::kShellWindowId_VirtualKeyboardContainer);
   views::Widget* widget = suggestion_window_view_->InitWidget();

ui/chromeos/ime/suggestion_view.cc

@@ -19,10 +19,9 @@ namespace {
 
 // Creates the suggestion label, and returns it (never returns nullptr).
 // The label text is not set in this function.
-views::Label* CreateSuggestionLabel() {
-  // Create the suggestion label. The label will be added to |this| as a
-  // child view, hence it's deleted when |this| is deleted.
-  views::Label* suggestion_label = new views::Label;
+std::unique_ptr<views::Label> CreateSuggestionLabel() {
+  std::unique_ptr<views::Label> suggestion_label =
+      std::make_unique<views::Label>();
 
   suggestion_label->SetFontList(kSuggestionFont);
   suggestion_label->SetEnabledColor(kSuggestionLabelColor);
@@ -34,8 +33,9 @@ views::Label* CreateSuggestionLabel() {
 }
 
 // Creates the "tab" annotation label, and return it (never returns nullptr).
-views::Label* CreateAnnotationLabel() {
-  views::Label* annotation_label = new views::Label;
+std::unique_ptr<views::Label> CreateAnnotationLabel() {
+  std::unique_ptr<views::Label> annotation_label =
+      std::make_unique<views::Label>();
   annotation_label->SetFontList(kAnnotationFont);
   annotation_label->SetEnabledColor(kSuggestionLabelColor);
   annotation_label->SetHorizontalAlignment(gfx::ALIGN_CENTER);
@@ -54,17 +54,13 @@ views::Label* CreateAnnotationLabel() {
 
 }  // namespace
 
-SuggestionView::SuggestionView()
-    : suggestion_label_(nullptr),
-      annotation_label_(nullptr),
-      suggestion_width_(0) {
-  suggestion_label_ = CreateSuggestionLabel();
-  annotation_label_ = CreateAnnotationLabel();
-
-  AddChildView(suggestion_label_);
-  AddChildView(annotation_label_);
+SuggestionView::SuggestionView() {
+  suggestion_label_ = AddChildView(CreateSuggestionLabel());
+  annotation_label_ = AddChildView(CreateAnnotationLabel());
 }
 
+SuggestionView::~SuggestionView() = default;
+
 void SuggestionView::SetText(const base::string16& text) {
   suggestion_label_->SetText(text);
   suggestion_width_ = suggestion_label_->GetPreferredSize().width();

ui/chromeos/ime/suggestion_view.h

@@ -39,7 +39,7 @@ constexpr SkColor kSuggestionLabelColor =
 class UI_CHROMEOS_EXPORT SuggestionView : public views::View {
  public:
   SuggestionView();
-  ~SuggestionView() override {}
+  ~SuggestionView() override;
 
   void SetText(const base::string16& text);
 
@@ -56,11 +56,11 @@ class UI_CHROMEOS_EXPORT SuggestionView : public views::View {
   // child views will be deleted when |this| is deleted.
 
   // The suggestion label renders suggestions.
-  views::Label* suggestion_label_;
+  views::Label* suggestion_label_ = nullptr;
   // The annotation label renders annotations.
-  views::Label* annotation_label_;
+  views::Label* annotation_label_ = nullptr;
 
-  int suggestion_width_;
+  int suggestion_width_ = 0;
 
   DISALLOW_COPY_AND_ASSIGN(SuggestionView);
 };

ui/chromeos/ime/suggestion_window_view.cc

@@ -66,12 +66,10 @@ SuggestionWindowView::SuggestionWindowView(gfx::NativeView parent,
 
   SetLayoutManager(std::make_unique<views::BoxLayout>(
       views::BoxLayout::Orientation::kVertical));
-
-  suggestion_view_ = new SuggestionView();
-  AddChildView(suggestion_view_);
+  suggestion_view_ = AddChildView(std::make_unique<SuggestionView>());
 }
 
-SuggestionWindowView::~SuggestionWindowView() {}
+SuggestionWindowView::~SuggestionWindowView() = default;
 
 views::Widget* SuggestionWindowView::InitWidget() {
   views::Widget* widget = BubbleDialogDelegateView::CreateBubble(this);