Have Chrome draw top window border when using custom titlebar.

chrome/browser/ui/views/frame/browser_desktop_window_tree_host_win.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 "chrome/browser/ui/views/frame/browser_desktop_window_tree_host_win.h"
 
 #include <dwmapi.h>
 
 #include "base/macros.h"
 #include "base/process/process_handle.h"
@@ skipping 155 matching lines @@
       // window is visible. We use this position to place the incognito avatar
       // in RTL mode, so when the window is shown, we need to re-layout and
       // schedule a paint for the non-client frame view so that the icon top has
       // the correct position when the window becomes visible. This fixes bugs
       // where the icon appears to overlay the minimize button. Note that we
       // will call Layout every time SetWindowPos is called with SWP_SHOWWINDOW,
       // however callers typically are careful about not specifying this flag
       // unless necessary to avoid flicker. This may be invoked during creation
       // on XP and before the non_client_view has been created.
       WINDOWPOS* window_pos = reinterpret_cast<WINDOWPOS*>(l_param);
-      if (window_pos->flags & SWP_SHOWWINDOW &&
-          GetWidget()->non_client_view()) {
-        GetWidget()->non_client_view()->Layout();
-        GetWidget()->non_client_view()->SchedulePaint();
+      auto* non_client_view = GetWidget()->non_client_view();
+      if (window_pos->flags & SWP_SHOWWINDOW && non_client_view) {
+        non_client_view->Layout();
+        non_client_view->SchedulePaint();
       }
       break;
     }
     case WM_ERASEBKGND: {
       gfx::Insets insets;
       if (!did_gdi_clear_ && GetClientAreaInsets(&insets)) {
         // This is necessary to avoid white flashing in the titlebar area around
         // the minimize/maximize/close buttons.
         DCHECK_EQ(0, insets.top());
         HDC dc = GetDC(hwnd);
         MARGINS margins = GetDWMFrameMargins();
         RECT client_rect;
         GetClientRect(hwnd, &client_rect);
         HBRUSH brush = CreateSolidBrush(0);
         RECT rect = {0, 0, client_rect.right, margins.cyTopHeight};
         FillRect(dc, &rect, brush);
         DeleteObject(brush);
         ReleaseDC(hwnd, dc);
         did_gdi_clear_ = true;
       }
       break;
     }
+    case WM_DWMCOLORIZATIONCOLORCHANGED: {
+      auto* non_client_view = GetWidget()->non_client_view();
+      // Activation border may have changed color.

[Peter Kasting, 2016/10/06 08:02:47]

Grammar Nazi Nit: Add "The" in front

+      if (non_client_view)
+        non_client_view->SchedulePaint();
+      break;
+    }
   }
 }
 
 views::FrameMode BrowserDesktopWindowTreeHostWin::GetFrameMode() const {
   const views::FrameMode system_frame_mode =
       browser_frame_->CustomDrawSystemTitlebar()
           ? views::FrameMode::SYSTEM_DRAWN_NO_CONTROLS
           : views::FrameMode::SYSTEM_DRAWN;
 
   // We don't theme popup or app windows, so regardless of whether or not a
@@ skipping 31 matching lines @@
 
 void BrowserDesktopWindowTreeHostWin::FrameTypeChanged() {
   views::DesktopWindowTreeHostWin::FrameTypeChanged();
   did_gdi_clear_ = false;
 }
 
 ////////////////////////////////////////////////////////////////////////////////
 // BrowserDesktopWindowTreeHostWin, private:
 
 void BrowserDesktopWindowTreeHostWin::UpdateDWMFrame() {
-  // With a custom titlebar we want the margins to always be 2 pixels, because
-  // that gives us the 1 pixel accent color border around the window (a 1 pixel
-  // margin is not sufficient, it will draw a messed-up-looking border instead).
-  // The other pixel ends up being 1-pixel-thick native titlebar (including
-  // caption buttons) but since we draw over that pixel in
-  // GlassBrowserFrameView::PaintTitlebar() it will be invisible and won't get
-  // mouse events.
-  if (browser_frame_->CustomDrawSystemTitlebar() && ShouldUseNativeFrame() &&
-      !GetWidget()->IsFullscreen()) {
-    MARGINS margins = {2, 2, 2, 2};
-    DwmExtendFrameIntoClientArea(GetHWND(), &margins);
-    return;
-  }
-
   // For "normal" windows on Aero, we always need to reset the glass area
   // correctly, even if we're not currently showing the native frame (e.g.
   // because a theme is showing), so we explicitly check for that case rather
   // than checking browser_frame_->ShouldUseNativeFrame() here.  Using that here
   // would mean we wouldn't reset the glass area to zero when moving from the
   // native frame to an opaque frame, leading to graphical glitches behind the
   // opaque frame.  Instead, we use that function below to tell us whether the
   // frame is currently native or opaque.
   if (!GetWidget()->client_view() || !browser_view_->IsBrowserTypeNormal() ||
       !DesktopWindowTreeHostWin::ShouldUseNativeFrame())
@@ skipping 15 matching lines @@
     return gfx::Insets();
 
   const ui::ThemeProvider* const tp = GetWidget()->GetThemeProvider();
     return gfx::Insets(
         0, tp->GetImageSkiaNamed(IDR_CONTENT_LEFT_SIDE)->width(),
         tp->GetImageSkiaNamed(IDR_CONTENT_BOTTOM_CENTER)->height(),
         tp->GetImageSkiaNamed(IDR_CONTENT_RIGHT_SIDE)->width());
 }
 
 MARGINS BrowserDesktopWindowTreeHostWin::GetDWMFrameMargins() const {
-  // If we're using the opaque frame or we're fullscreen we don't extend the
-  // glass in at all because it won't be visible.
-  if (!ShouldUseNativeFrame() || GetWidget()->IsFullscreen())
+  // If we're using the opaque frame or custom titlebar or we're fullscreen we
+  // don't extend the glass in at all because it won't be visible.

[Peter Kasting, 2016/10/06 08:02:47]

Nit: Clearer (to me):

Don't extend the DWM frame in unless we're letting the DWM draw a non-maximized,
non-fullscreen window.  Outside that scenario, no DWM-drawn area will be
visible.

[Bret, 2016/10/06 20:48:10]

Not quite accurate because DWM still draws non-client area, and it doesn't
explain why the custom titlebar part is important unless you're familiar with
how it works. I think the comment is okay as is.

[Peter Kasting, 2016/10/11 20:01:38]

What about:

Don't extend the DWM frame in unless we're letting the DWM draw a non-maximized,
non-fullscreen window.  Outside that scenario, the DWM will not be drawing in
the window client area.

This corrects the inaccuracy you mention.  The reason I'm suggesting a change is
because I'd like to spend less time restating the code and more time on "why". 
It's subtle, though.

[Bret, 2016/10/11 20:48:19]

Okay, I agree about not restating the code. Maybe this doesn't need a comment at
all? Or if you think it does, maybe just "Don't extend the DWM frame in when it
won't be visible." I still think "won't be visible" is more accurate because DWM
still draws things when even when we draw over it (you can tell if Chrome dies
somehow and only the Windows-drawn area is visible).

[Peter Kasting, 2016/10/11 20:56:51]

I like your simple comment suggestion.

+  if (!ShouldUseNativeFrame() || GetWidget()->IsFullscreen() ||
+      browser_frame_->CustomDrawSystemTitlebar())
     return MARGINS{0};
 
   // The glass should extend to the bottom of the tabstrip.
   HWND hwnd = GetHWND();
   gfx::Rect tabstrip_bounds(
       browser_frame_->GetBoundsForTabStrip(browser_view_->tabstrip()));
   tabstrip_bounds =
       display::win::ScreenWin::DIPToClientRect(hwnd, tabstrip_bounds);
 
   // Extend inwards far enough to go under the semitransparent client edges.
@@ skipping 23 matching lines @@
     BrowserDesktopWindowTreeHost::CreateBrowserDesktopWindowTreeHost(
         views::internal::NativeWidgetDelegate* native_widget_delegate,
         views::DesktopNativeWidgetAura* desktop_native_widget_aura,
         BrowserView* browser_view,
         BrowserFrame* browser_frame) {
   return new BrowserDesktopWindowTreeHostWin(native_widget_delegate,
                                              desktop_native_widget_aura,
                                              browser_view,
                                              browser_frame);
 }