Adds NewTabPromo as a member of NewTabButton to support browsertests

Changes this CL:
- Renames NewTabPromo::CreateSelfOwned to NewTabPromo::Create.
- Adds a NewTabPromo as a member variable of NewTabButton for the following reasons:
1. To make the promo more accessible in order to check visibility in browsertests.
2. To tie the NewTabPromo to the specific NewTabButton it is being shown by. 

Bug: 734132
Change-Id: I71993f0185d712b62ac98706b165b078c4bb574b
Reviewed-on: https://chromium-review.googlesource.com/594627
Commit-Queue: Christopher Benson <chrisbenson@google.com>
Reviewed-by: Peter Kasting <pkasting@chromium.org>
Cr-Commit-Position: refs/heads/master@{#491625}

chrome/browser/ui/views/tabs/new_tab_button.cc

@@ -53,6 +53,7 @@ sk_sp<SkDrawLooper> CreateShadowDrawLooper(SkColor color) {
 NewTabButton::NewTabButton(TabStrip* tab_strip, views::ButtonListener* listener)
     : views::ImageButton(listener),
       tab_strip_(tab_strip),
+      new_tab_promo_(nullptr),
       destroyed_(nullptr),
       new_tab_promo_observer_(this) {
   set_animate_on_state_change(true);
@@ -78,8 +79,8 @@ int NewTabButton::GetTopOffset() {
 
 void NewTabButton::ShowPromo() {
   // Owned by its native widget. Will be destroyed as its widget is destroyed.
-  NewTabPromo* new_tab_promo = NewTabPromo::CreateSelfOwned(GetVisibleBounds());
-  new_tab_promo_observer_.Add(new_tab_promo->GetWidget());
+  new_tab_promo_ = NewTabPromo::Create(GetVisibleBounds());
+  new_tab_promo_observer_.Add(new_tab_promo_->GetWidget());
   NewTabButton::SchedulePaint();
 }
 

chrome/browser/ui/views/tabs/new_tab_button.h

@@ -41,6 +41,8 @@ class NewTabButton : public views::ImageButton,
   // Shows the NewTabPromo when the NewTabFeatureEngagementTracker calls for it.
   void ShowPromo();
 
+  NewTabPromo* new_tab_promo() { return new_tab_promo_; }
+
  private:
 // views::ImageButton:
 #if defined(OS_WIN)
@@ -81,6 +83,10 @@ class NewTabButton : public views::ImageButton,
   // Tab strip that contains this button.
   TabStrip* tab_strip_;
 
+  // Promotional UI that appears next to the NewTabButton and encourages its
+  // use. Owned by its NativeWidget.
+  NewTabPromo* new_tab_promo_;
+
   // The offset used to paint the background image.
   gfx::Point background_offset_;
 

chrome/browser/ui/views/tabs/new_tab_promo.cc

@@ -33,7 +33,7 @@ constexpr base::TimeDelta kBubbleCloseDelayShort =
 }  // namespace
 
 // static
-NewTabPromo* NewTabPromo::CreateSelfOwned(const gfx::Rect& anchor_rect) {
+NewTabPromo* NewTabPromo::Create(const gfx::Rect& anchor_rect) {
   return new NewTabPromo(anchor_rect);
 }
 

chrome/browser/ui/views/tabs/new_tab_promo.h

@@ -22,8 +22,9 @@ class MouseEvent;
 // when prompted by the NewTabFeatureEngagementTracker.
 class NewTabPromo : public views::BubbleDialogDelegateView {
  public:
-  // Returns a self owned raw pointer to the NewTabButton.
-  static NewTabPromo* CreateSelfOwned(const gfx::Rect& anchor_rect);
+  // Returns a raw pointer to the NewTabButton. This raw pointer is owned by its
+  // NativeWidget.
+  static NewTabPromo* Create(const gfx::Rect& anchor_rect);
 
  private:
   // Constructs NewTabPromo. Anchors the bubble to the NewTabButton.