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 83 matching lines @@
     return false;
 
   if (GetWidget()->IsFullscreen()) {
     // In fullscreen mode there is no frame.
     *insets = gfx::Insets();
   } else {
     const int frame_thickness =
         display::win::ScreenWin::GetSystemMetricsForHwnd(
             GetHWND(), SM_CXSIZEFRAME);
     // Reduce the Windows non-client border size because we extend the border
-    // into our client area in UpdateDWMFrame().
+    // into our client area in UpdateDWMFrame(). The top inset must be 0 or
+    // else DWM will draw a full native titlebar outside the client area.

[Bret, 2016/10/07 18:21:56]

nit: Windows, not DWM

     *insets = gfx::Insets(0, frame_thickness, frame_thickness,
                           frame_thickness) - GetClientEdgeThicknesses();
   }
   return true;
 }
 
 void BrowserDesktopWindowTreeHostWin::HandleCreate() {
   DesktopWindowTreeHostWin::HandleCreate();
   browser_window_property_manager_ =
       BrowserWindowPropertyManager::CreateBrowserWindowPropertyManager(
@@ skipping 51 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();

[Bret, 2016/10/07 18:21:56]

nit: use NonClientView

+      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();

[Bret, 2016/10/07 18:21:56]

nit: here too

+      // The activation border may have changed color.
+      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.
+  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);
 }