Reland "Removed BrowserView::ViewHierarchChanged, moved most code to...

Reland "Removed BrowserView::ViewHierarchChanged, moved most code to constructor and widget-specfic code to AddedToWidget."

This is a reland of f3616c26

Original change's description:
> Removed BrowserView::ViewHierarchChanged, moved most code to constructor and widget-specfic code to AddedToWidget.
> 
> Bug: 245409
> Change-Id: I1e606548df4361199862c561ad86f4d40cbaa7df
> Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1979098
> Commit-Queue: Allen Bauer <kylixrd@chromium.org>
> Reviewed-by: Peter Kasting <pkasting@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#728998}

Bug: 245409
Change-Id: Id5317849e130ec8715200f0947bc01f2bc932842
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1991945
Commit-Queue: Peter Kasting <pkasting@chromium.org>
Reviewed-by: Peter Kasting <pkasting@chromium.org>
Cr-Commit-Position: refs/heads/master@{#729914}

chrome/browser/ui/views/frame/browser_non_client_frame_view.cc

@@ -46,7 +46,10 @@ BrowserNonClientFrameView::BrowserNonClientFrameView(BrowserFrame* frame,
     g_browser_process->profile_manager()->
         GetProfileAttributesStorage().AddObserver(this);
   }
-  MaybeObserveTabstrip();
+  if (browser_view_->tabstrip()) {
+    DCHECK(!tab_strip_observer_.IsObserving(browser_view_->tabstrip()));
+    tab_strip_observer_.Add(browser_view_->tabstrip());
+  }
 }
 
 BrowserNonClientFrameView::~BrowserNonClientFrameView() {
@@ -58,7 +61,6 @@ BrowserNonClientFrameView::~BrowserNonClientFrameView() {
 }
 
 void BrowserNonClientFrameView::OnBrowserViewInitViewsComplete() {
-  MaybeObserveTabstrip();
   UpdateMinimumSize();
 }
 
@@ -385,13 +387,6 @@ int BrowserNonClientFrameView::GetSystemMenuY() const {
 }
 #endif
 
-void BrowserNonClientFrameView::MaybeObserveTabstrip() {
-  if (browser_view_->tabstrip()) {
-    DCHECK(!tab_strip_observer_.IsObserving(browser_view_->tabstrip()));
-    tab_strip_observer_.Add(browser_view_->tabstrip());
-  }
-}
-
 const ui::ThemeProvider*
 BrowserNonClientFrameView::GetThemeProviderForProfile() const {
   // Because the frame's accessor reads the ThemeProvider from the profile and

chrome/browser/ui/views/frame/browser_non_client_frame_view.h

@@ -177,8 +177,6 @@ class BrowserNonClientFrameView : public views::NonClientFrameView,
   int GetSystemMenuY() const override;
 #endif
 
-  void MaybeObserveTabstrip();
-
   // Gets a theme provider that should be non-null even before we're added to a
   // view hierarchy.
   const ui::ThemeProvider* GetThemeProviderForProfile() const;

chrome/browser/ui/views/frame/browser_view.h

@@ -498,6 +498,7 @@ class BrowserView : public BrowserWindow,
   void OnGestureEvent(ui::GestureEvent* event) override;
   void ViewHierarchyChanged(
       const views::ViewHierarchyChangedDetails& details) override;
+  void AddedToWidget() override;
   void PaintChildren(const views::PaintInfo& paint_info) override;
   void OnBoundsChanged(const gfx::Rect& previous_bounds) override;
   void ChildPreferredSizeChanged(View* child) override;
@@ -579,9 +580,6 @@ class BrowserView : public BrowserWindow,
   // affected.
   void RevealTabStripIfNeeded();
 
-  // Constructs and initializes the child views.
-  void InitViews();
-
   // Make sure the WebUI tab strip exists if it should.
   void MaybeInitializeWebUITabStrip();