Remove the code for detecting changes in custom state

ShouldCustomDrawSystemTitlebar will never change during the runtime of
the browser now so these checks are unnecessary.

Bug: 953982
Change-Id: Icc9e8201a0e23fe0eab9cfe62d1a9d2a2290af88
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2108128Reviewed-by: Peter Kasting <pkasting@chromium.org>
Commit-Queue: Peter Kasting <pkasting@chromium.org>
Cr-Commit-Position: refs/heads/master@{#751220}

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

@@ -1735,12 +1735,6 @@ void BrowserView::UserChangedTheme(BrowserThemeChangeType theme_change_type) {
   must_regenerate_frame |=
       theme_change_type == BrowserThemeChangeType::kBrowserTheme &&
       !IsFullscreen();
-
-  // TODO(https://crbug.com/953982): Remove the need to regenerate the frame
-  const bool should_use_custom_titlebar = ShouldCustomDrawSystemTitlebar();
-
-  must_regenerate_frame |=
-      (using_custom_titlebar_ != should_use_custom_titlebar);
 #else
   must_regenerate_frame |=
       theme_change_type == BrowserThemeChangeType::kBrowserTheme;
@@ -1756,10 +1750,6 @@ void BrowserView::UserChangedTheme(BrowserThemeChangeType theme_change_type) {
     GetWidget()->ThemeChanged();
   }
   using_native_frame_ = should_use_native_frame;
-
-#if defined(OS_WIN)
-  using_custom_titlebar_ = should_use_custom_titlebar;
-#endif
 }
 
 void BrowserView::ShowAppMenu() {

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

@@ -807,12 +807,6 @@ class BrowserView : public BrowserWindow,
   // True if (as of the last time it was checked) the frame type is native.
   bool using_native_frame_ = true;
 
-#if defined(OS_WIN)
-  // True if (as of the last time it was checked) we're using a custom drawn
-  // title bar.
-  bool using_custom_titlebar_ = true;
-#endif
-
   // True when in ProcessFullscreen(). The flag is used to avoid reentrance and
   // to ignore requests to layout while in ProcessFullscreen() to reduce
   // jankiness.