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 181 matching lines @@
         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:
+      // Activation border may have changed color.
+      if (GetWidget()->non_client_view())

[Peter Kasting, 2016/10/01 05:00:14]

Nit: Consider a temp (maybe with auto*) to avoid duplicated calls here (but if
so, consider also fixing the WM_WINDOWPOSCHANGED case similarly).

+        GetWidget()->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 41 matching lines @@
   // 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);

[Bret, 2016/10/01 19:53:08]

If the client area is fully opaque then this block shouldn't be necessary any
more.

     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
@@ skipping 64 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);
 }