diff --git content/browser/renderer_host/render_widget_host_view_base.cc content/browser/renderer_host/render_widget_host_view_base.cc
index 934195fd77d2..8aec87d4a448 100644
--- content/browser/renderer_host/render_widget_host_view_base.cc
+++ content/browser/renderer_host/render_widget_host_view_base.cc
@@ -560,6 +560,14 @@ float RenderWidgetHostViewBase::GetDeviceScaleFactor() {
   return screen_info.device_scale_factor;
 }
 
+void RenderWidgetHostViewBase::SetHasExternalParent(bool val) {
+  has_external_parent_ = val;
+}
+
+bool RenderWidgetHostViewBase::HasExternalParent() const {
+  return has_external_parent_;
+}
+
 uint32_t RenderWidgetHostViewBase::RendererFrameNumber() {
   return renderer_frame_number_;
 }
diff --git content/browser/renderer_host/render_widget_host_view_base.h content/browser/renderer_host/render_widget_host_view_base.h
index af80b343dcd9..507618362acd 100644
--- content/browser/renderer_host/render_widget_host_view_base.h
+++ content/browser/renderer_host/render_widget_host_view_base.h
@@ -65,6 +65,7 @@ class CursorManager;
 class MouseWheelPhaseHandler;
 class RenderWidgetHostImpl;
 class RenderWidgetHostViewBaseObserver;
+class RenderWidgetHostViewGuest;
 class SyntheticGestureTarget;
 class TextInputManager;
 class TouchSelectionControllerClientManager;
@@ -82,6 +83,9 @@ class CONTENT_EXPORT RenderWidgetHostViewBase
   float current_device_scale_factor() const {
     return current_device_scale_factor_;
   }
+  void set_current_device_scale_factor(float scale_factor) {
+    current_device_scale_factor_ = scale_factor;
+  }
 
   // Returns the focused RenderWidgetHost inside this |view|'s RWH.
   RenderWidgetHostImpl* GetFocusedWidget() const;
@@ -116,6 +120,8 @@ class CONTENT_EXPORT RenderWidgetHostViewBase
   void DisableAutoResize(const gfx::Size& new_size) override;
   bool IsScrollOffsetAtTop() override;
   float GetDeviceScaleFactor() final;
+  void SetHasExternalParent(bool val) override;
+  bool HasExternalParent() const override;
   TouchSelectionControllerClientManager*
   GetTouchSelectionControllerClientManager() override;
   void SetRecordContentToVisibleTimeRequest(
@@ -439,6 +445,12 @@ class CONTENT_EXPORT RenderWidgetHostViewBase
   // helps to position the full screen widget on the correct monitor.
   virtual void InitAsFullscreen(RenderWidgetHostView* reference_host_view) = 0;
 
+  // Perform all the initialization steps necessary for this object to represent
+  // the platform widget owned by |guest_view| and embedded in
+  // |parent_host_view|.
+  virtual void InitAsGuest(RenderWidgetHostView* parent_host_view,
+                           RenderWidgetHostViewGuest* guest_view) {}
+
   // Sets the cursor for this view to the one associated with the specified
   // cursor_type.
   virtual void UpdateCursor(const WebCursor& cursor) = 0;
@@ -620,6 +632,10 @@ class CONTENT_EXPORT RenderWidgetHostViewBase
   // specific RenderWidgetHostView.
   base::Optional<DisplayFeature> display_feature_;
 
+  // True if the widget has a external parent view/window outside of the
+  // Chromium-controlled view/window hierarchy.
+  bool has_external_parent_ = false;
+
  private:
   FRIEND_TEST_ALL_PREFIXES(
       BrowserSideFlingBrowserTest,
diff --git content/browser/renderer_host/render_widget_host_view_event_handler.cc content/browser/renderer_host/render_widget_host_view_event_handler.cc
index 44586cc1789a..18705ef4e6e7 100644
--- content/browser/renderer_host/render_widget_host_view_event_handler.cc
+++ content/browser/renderer_host/render_widget_host_view_event_handler.cc
@@ -37,6 +37,10 @@
 #include "ui/events/keycodes/dom/dom_code.h"
 #include "ui/touch_selection/touch_selection_controller.h"
 
+#if defined(OS_LINUX)
+#include "ui/aura/window_tree_host.h"
+#endif
+
 #if defined(OS_WIN)
 #include "content/browser/frame_host/render_frame_host_impl.h"
 #include "ui/aura/window_tree_host.h"
@@ -954,6 +958,14 @@ void RenderWidgetHostViewEventHandler::MoveCursorToCenter(
     }
     return;
   }
+#endif
+#if defined(OS_LINUX)
+  if (host_view_->HasExternalParent() &&
+      window_ && window_->delegate()->CanFocus()) {
+    aura::WindowTreeHost* host = window_->GetHost();
+    if (host)
+      host->Show();
+  }
 #endif
   synthetic_move_position_ = center_in_screen;
 }
diff --git content/public/browser/render_widget_host_view.h content/public/browser/render_widget_host_view.h
index a7222155f4ea..77ac1f864161 100644
--- content/public/browser/render_widget_host_view.h
+++ content/public/browser/render_widget_host_view.h
@@ -243,6 +243,14 @@ class CONTENT_EXPORT RenderWidgetHostView {
   // This must always return the same device scale factor as GetScreenInfo.
   virtual float GetDeviceScaleFactor() = 0;
 
+  // Set whether the widget has a external parent view/window outside of the
+  // Chromium-controlled view/window hierarchy.
+  virtual void SetHasExternalParent(bool val) = 0;
+
+  // Returns true if the widget has a external parent view/window outside of the
+  // Chromium-controlled view/window hierarchy.
+  virtual bool HasExternalParent() const = 0;
+
 #if defined(OS_MAC)
   // Set the view's active state (i.e., tint state of controls).
   virtual void SetActive(bool active) = 0;
diff --git ui/base/x/x11_window.cc ui/base/x/x11_window.cc
index 24dbb60257bb..59e731f9ba0b 100644
--- ui/base/x/x11_window.cc
+++ ui/base/x/x11_window.cc
@@ -272,7 +272,8 @@ void XWindow::Init(const Configuration& config) {
   req.border_pixel = 0;
 
   bounds_in_pixels_ = SanitizeBounds(config.bounds);
-  req.parent = x_root_window_;
+  req.parent = config.parent_widget == gfx::kNullAcceleratedWidget ?
+      x_root_window_ : static_cast<x11::Window>(config.parent_widget);
   req.x = bounds_in_pixels_.x();
   req.y = bounds_in_pixels_.y();
   req.width = bounds_in_pixels_.width();
diff --git ui/base/x/x11_window.h ui/base/x/x11_window.h
index af282d4190dd..147a2cd9ac4c 100644
--- ui/base/x/x11_window.h
+++ ui/base/x/x11_window.h
@@ -21,6 +21,7 @@
 #include "ui/gfx/geometry/rect.h"
 #include "ui/gfx/geometry/size.h"
 #include "ui/gfx/geometry/size_f.h"
+#include "ui/gfx/native_widget_types.h"
 #include "ui/gfx/x/event.h"
 #include "ui/gfx/x/sync.h"
 #include "ui/gfx/x/x11.h"
@@ -93,6 +94,7 @@ class COMPONENT_EXPORT(UI_BASE_X) XWindow {
     std::string wm_class_name;
     std::string wm_class_class;
     std::string wm_role_name;
+    gfx::AcceleratedWidget parent_widget = gfx::kNullAcceleratedWidget;
   };
 
   XWindow();
diff --git ui/platform_window/x11/x11_window.cc ui/platform_window/x11/x11_window.cc
index c0ba5c3a156e..c12372d6e435 100644
--- ui/platform_window/x11/x11_window.cc
+++ ui/platform_window/x11/x11_window.cc
@@ -93,6 +93,7 @@ ui::XWindow::Configuration ConvertInitPropertiesToXWindowConfig(
   config.wm_class_class = properties.wm_class_class;
   config.wm_role_name = properties.wm_role_name;
   config.activatable = properties.activatable;
+  config.parent_widget = properties.parent_widget;
   config.prefer_dark_theme = properties.prefer_dark_theme;
   config.background_color = properties.background_color;
   return config;
diff --git ui/views/widget/desktop_aura/desktop_screen_win.cc ui/views/widget/desktop_aura/desktop_screen_win.cc
index e9bb45ad238c..68f2a5ef5d0c 100644
--- ui/views/widget/desktop_aura/desktop_screen_win.cc
+++ ui/views/widget/desktop_aura/desktop_screen_win.cc
@@ -18,6 +18,8 @@ DesktopScreenWin::~DesktopScreenWin() {
 }
 
 HWND DesktopScreenWin::GetHWNDFromNativeWindow(gfx::NativeWindow window) const {
+  if (!window)
+    return nullptr;  
   aura::WindowTreeHost* host = window->GetHost();
   return host ? host->GetAcceleratedWidget() : nullptr;
 }
diff --git ui/views/widget/desktop_aura/desktop_window_tree_host_linux.cc ui/views/widget/desktop_aura/desktop_window_tree_host_linux.cc
index 0bdc1470708b..0f1d6960f0ea 100644
--- ui/views/widget/desktop_aura/desktop_window_tree_host_linux.cc
+++ ui/views/widget/desktop_aura/desktop_window_tree_host_linux.cc
@@ -187,6 +187,18 @@ Widget::MoveLoopResult DesktopWindowTreeHostLinux::RunMoveLoop(
                                                     escape_behavior);
 }
 
+gfx::Rect DesktopWindowTreeHostLinux::GetWindowBoundsInScreen() const {
+  if (!screen_bounds_.IsEmpty())
+    return screen_bounds_;
+  return DesktopWindowTreeHostPlatform::GetWindowBoundsInScreen();
+}
+
+gfx::Point DesktopWindowTreeHostLinux::GetLocationOnScreenInPixels() const {
+  if (!screen_bounds_.IsEmpty())
+    return screen_bounds_.origin();
+  return DesktopWindowTreeHostPlatform::GetLocationOnScreenInPixels();
+}
+
 void DesktopWindowTreeHostLinux::DispatchEvent(ui::Event* event) {
   // The input can be disabled and the widget marked as non-active in case of
   // opened file-dialogs.
@@ -319,6 +331,8 @@ void DesktopWindowTreeHostLinux::AddAdditionalInitProperties(
   properties->wm_class_class = params.wm_class_class;
   properties->wm_role_name = params.wm_role_name;
 
+  properties->parent_widget = params.parent_widget;
+
   DCHECK(!properties->x11_extension_delegate);
   properties->x11_extension_delegate = this;
 }
diff --git ui/views/widget/desktop_aura/desktop_window_tree_host_linux.h ui/views/widget/desktop_aura/desktop_window_tree_host_linux.h
index 4b6a5a4476a3..c9881d4a716c 100644
--- ui/views/widget/desktop_aura/desktop_window_tree_host_linux.h
+++ ui/views/widget/desktop_aura/desktop_window_tree_host_linux.h
@@ -68,6 +68,8 @@ class VIEWS_EXPORT DesktopWindowTreeHostLinux
   // Disables event listening to make |dialog| modal.
   base::OnceClosure DisableEventListening();
 
+  void set_screen_bounds(const gfx::Rect& bounds) { screen_bounds_ = bounds; }
+
  protected:
   // Overridden from DesktopWindowTreeHost:
   void Init(const Widget::InitParams& params) override;
@@ -78,6 +80,8 @@ class VIEWS_EXPORT DesktopWindowTreeHostLinux
       const gfx::Vector2d& drag_offset,
       Widget::MoveLoopSource source,
       Widget::MoveLoopEscapeBehavior escape_behavior) override;
+  gfx::Rect GetWindowBoundsInScreen() const override;
+  gfx::Point GetLocationOnScreenInPixels() const override;
 
   // PlatformWindowDelegate:
   void DispatchEvent(ui::Event* event) override;
@@ -134,6 +138,9 @@ class VIEWS_EXPORT DesktopWindowTreeHostLinux
   // destroyed.
   static std::list<gfx::AcceleratedWidget>* open_windows_;
 
+   // Override the screen bounds when the host is a child window.
+  gfx::Rect screen_bounds_;
+
   // The display and the native X window hosting the root window.
   base::WeakPtrFactory<DesktopWindowTreeHostLinux> weak_factory_{this};
 
diff --git ui/views/widget/desktop_aura/desktop_window_tree_host_win.cc ui/views/widget/desktop_aura/desktop_window_tree_host_win.cc
index e9e61a24dc87..7687ded2a82e 100644
--- ui/views/widget/desktop_aura/desktop_window_tree_host_win.cc
+++ ui/views/widget/desktop_aura/desktop_window_tree_host_win.cc
@@ -140,8 +140,12 @@ void DesktopWindowTreeHostWin::Init(const Widget::InitParams& params) {
                         native_widget_delegate_);
 
   HWND parent_hwnd = nullptr;
-  if (params.parent && params.parent->GetHost())
+  if (params.parent_widget) {
+    parent_hwnd = params.parent_widget;
+    has_external_parent_ = true;
+  } else if (params.parent && params.parent->GetHost()) {
     parent_hwnd = params.parent->GetHost()->GetAcceleratedWidget();
+  }
 
   remove_standard_frame_ = params.remove_standard_frame;
   has_non_client_view_ = Widget::RequiresNonClientView(params.type);
@@ -915,11 +919,15 @@ void DesktopWindowTreeHostWin::HandleFrameChanged() {
 }
 
 void DesktopWindowTreeHostWin::HandleNativeFocus(HWND last_focused_window) {
-  // TODO(beng): inform the native_widget_delegate_.
+  // See comments in CefBrowserHostImpl::PlatformSetFocus.
+  if (has_external_parent_ && CanActivate())
+    HandleActivationChanged(true);
 }
 
 void DesktopWindowTreeHostWin::HandleNativeBlur(HWND focused_window) {
-  // TODO(beng): inform the native_widget_delegate_.
+  // See comments in CefBrowserHostImpl::PlatformSetFocus.
+  if (has_external_parent_ && CanActivate())
+    HandleActivationChanged(false);
 }
 
 bool DesktopWindowTreeHostWin::HandleMouseEvent(ui::MouseEvent* event) {
diff --git ui/views/widget/desktop_aura/desktop_window_tree_host_win.h ui/views/widget/desktop_aura/desktop_window_tree_host_win.h
index 0229c1c41502..992f89126f7f 100644
--- ui/views/widget/desktop_aura/desktop_window_tree_host_win.h
+++ ui/views/widget/desktop_aura/desktop_window_tree_host_win.h
@@ -293,6 +293,10 @@ class VIEWS_EXPORT DesktopWindowTreeHostWin
   // True if the window should have the frame removed.
   bool remove_standard_frame_;
 
+  // True if the widget has a external parent view/window outside of the
+  // Chromium-controlled view/window hierarchy.
+  bool has_external_parent_ = false;
+
   // Owned by TooltipController, but we need to forward events to it so we keep
   // a reference.
   corewm::TooltipWin* tooltip_;
diff --git ui/views/widget/widget.cc ui/views/widget/widget.cc
index f02508580d16..a2be2ed6aa2d 100644
--- ui/views/widget/widget.cc
+++ ui/views/widget/widget.cc
@@ -285,7 +285,8 @@ void Widget::Init(InitParams params) {
     params.name = params.delegate->GetContentsView()->GetClassName();
 
   params.child |= (params.type == InitParams::TYPE_CONTROL);
-  is_top_level_ = !params.child;
+  is_top_level_ = !params.child ||
+                  params.parent_widget != gfx::kNullAcceleratedWidget;
 
   if (params.opacity == views::Widget::InitParams::WindowOpacity::kInferred &&
       params.type != views::Widget::InitParams::TYPE_WINDOW) {
@@ -369,7 +370,12 @@ void Widget::Init(InitParams params) {
     }
   } else if (delegate) {
     SetContentsView(delegate->GetContentsView());
-    SetInitialBoundsForFramelessWindow(bounds);
+    if (params.parent_widget != gfx::kNullAcceleratedWidget) {
+      // Set the bounds directly instead of applying an inset.
+      SetBounds(bounds);
+    } else {
+      SetInitialBoundsForFramelessWindow(bounds);
+    }
   }
 
   observer_manager_.Add(GetNativeTheme());
@@ -1153,10 +1159,16 @@ void Widget::OnNativeWidgetDestroyed() {
 }
 
 gfx::Size Widget::GetMinimumSize() const {
+  gfx::Size size;
+  if (widget_delegate_->MaybeGetMinimumSize(&size))
+    return size;
   return non_client_view_ ? non_client_view_->GetMinimumSize() : gfx::Size();
 }
 
 gfx::Size Widget::GetMaximumSize() const {
+  gfx::Size size;
+  if (widget_delegate_->MaybeGetMaximumSize(&size))
+    return size;
   return non_client_view_ ? non_client_view_->GetMaximumSize() : gfx::Size();
 }
 
diff --git ui/views/widget/widget.h ui/views/widget/widget.h
index 032f77d5738a..085c4df9fa8c 100644
--- ui/views/widget/widget.h
+++ ui/views/widget/widget.h
@@ -315,6 +315,8 @@ class VIEWS_EXPORT Widget : public internal::NativeWidgetDelegate,
     // the concept with bubble anchoring a la BubbleDialogDelegateView.
     gfx::NativeView parent = nullptr;
 
+    gfx::AcceleratedWidget parent_widget = gfx::kNullAcceleratedWidget;
+
     // Specifies the initial bounds of the Widget. Default is empty, which means
     // the NativeWidget may specify a default size. If the parent is specified,
     // |bounds| is in the parent's coordinate system. If the parent is not
diff --git ui/views/widget/widget_delegate.h ui/views/widget/widget_delegate.h
index fdf697d54693..d21effca6422 100644
--- ui/views/widget/widget_delegate.h
+++ ui/views/widget/widget_delegate.h
@@ -301,6 +301,10 @@ class VIEWS_EXPORT WidgetDelegate {
   // Returns true if the title text should be centered.
   bool ShouldCenterWindowTitleText() const;
 
+  // CEF supports override of min/max size values.
+  virtual bool MaybeGetMinimumSize(gfx::Size* size) const { return false; }
+  virtual bool MaybeGetMaximumSize(gfx::Size* size) const { return false; }
+
   bool focus_traverses_out() const { return params_.focus_traverses_out; }
 
  private:
diff --git ui/views/widget/widget_hwnd_utils.cc ui/views/widget/widget_hwnd_utils.cc
index 89f5b62f95df..8f6971929a12 100644
--- ui/views/widget/widget_hwnd_utils.cc
+++ ui/views/widget/widget_hwnd_utils.cc
@@ -67,7 +67,7 @@ void CalculateWindowStylesFromInitParams(
       if (!widget_delegate->CanResize())
         *style &= ~(WS_THICKFRAME | WS_MAXIMIZEBOX);
       if (params.remove_standard_frame)
-        *style &= ~(WS_MINIMIZEBOX | WS_MAXIMIZEBOX);
+        *style &= ~(WS_MINIMIZEBOX | WS_MAXIMIZEBOX | WS_CAPTION | WS_SYSMENU);
 
       if (native_widget_delegate->IsDialogBox()) {
         *style |= DS_MODALFRAME;
diff --git ui/views/win/hwnd_message_handler.cc ui/views/win/hwnd_message_handler.cc
index 5e8d267d868d..414e20ad8203 100644
--- ui/views/win/hwnd_message_handler.cc
+++ ui/views/win/hwnd_message_handler.cc
@@ -3071,10 +3071,13 @@ LRESULT HWNDMessageHandler::HandleMouseEventInternal(UINT message,
   } else if (event.type() == ui::ET_MOUSEWHEEL) {
     ui::MouseWheelEvent mouse_wheel_event(msg);
     // Reroute the mouse wheel to the window under the pointer if applicable.
-    return (ui::RerouteMouseWheel(hwnd(), w_param, l_param) ||
-            delegate_->HandleMouseEvent(&mouse_wheel_event))
-               ? 0
-               : 1;
+    if (ui::RerouteMouseWheel(hwnd(), w_param, l_param) ||
+        delegate_->HandleMouseEvent(&mouse_wheel_event)) {
+      SetMsgHandled(TRUE);
+      return 0;
+    } else {
+      return 1;
+    }
   }
 
   // Suppress |ET_MOUSE_MOVED| and |ET_MOUSE_DRAGGED| events from WM_MOUSE*