Clip the header of ash windows to the frame height

ash/wm/custom_frame_view_ash.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 "ash/wm/custom_frame_view_ash.h"
 
 #include "ash/wm/frame_painter.h"
 #include "ash/wm/workspace/frame_maximize_button.h"
 #include "grit/ash_resources.h"
 #include "grit/ui_strings.h"  // Accessibility names
 #include "ui/base/l10n/l10n_util.h"
 #include "ui/base/resource/resource_bundle.h"
 #include "ui/compositor/layer_animator.h"
+#include "ui/gfx/canvas.h"
 #include "ui/gfx/font.h"
 #include "ui/gfx/image/image.h"
 #include "ui/gfx/rect.h"
 #include "ui/gfx/size.h"
 #include "ui/views/controls/button/image_button.h"
 #include "ui/views/widget/native_widget_aura.h"
 #include "ui/views/widget/widget.h"
 #include "ui/views/widget/widget_delegate.h"
 
 namespace {
@@ skipping 97 matching lines @@
 
 void CustomFrameViewAsh::Layout() {
   // Use the shorter maximized layout headers.
   frame_painter_->LayoutHeader(this, true);
 }
 
 void CustomFrameViewAsh::OnPaint(gfx::Canvas* canvas) {
   if (frame_->IsFullscreen())
     return;
 
+  // Prevent bleeding paint onto the client area below the window frame, which
+  // may become visible when the WebContent is transparent.
+  canvas->Save();
+  canvas->ClipRect(gfx::Rect(0, 0, width(), NonClientTopBorderHeight()));
+
   bool paint_as_active = ShouldPaintAsActive();
   int theme_image_id = paint_as_active ? IDR_AURA_WINDOW_HEADER_BASE_ACTIVE :
       IDR_AURA_WINDOW_HEADER_BASE_INACTIVE;
   frame_painter_->PaintHeader(
       this,
       canvas,
       paint_as_active ? FramePainter::ACTIVE : FramePainter::INACTIVE,
       theme_image_id,
       NULL);
   frame_painter_->PaintTitleBar(this, canvas, GetTitleFont());
   frame_painter_->PaintHeaderContentSeparator(this, canvas);
+  canvas->Restore();
 }
 
 std::string CustomFrameViewAsh::GetClassName() const {
   return kViewClassName;
 }
 
 gfx::Size CustomFrameViewAsh::GetMinimumSize() {
   return frame_painter_->GetMinimumSize(this);
 }
 
@@ skipping 29 matching lines @@
   if (frame_->IsFullscreen())
     return 0;
 
   // Reserve enough space to see the buttons, including any offset from top and
   // reserving space for the separator line.
   return close_button_->bounds().bottom() +
       frame_painter_->HeaderContentSeparatorSize();
 }
 
 }  // namespace ash