Allows menu host windows to be enumerated in DragTargetWindowFinder

ui/views/widget/desktop_aura/x11_whole_screen_move_loop.cc

Index: ui/views/widget/desktop_aura/x11_whole_screen_move_loop.cc
diff --git a/ui/views/widget/desktop_aura/x11_whole_screen_move_loop.cc b/ui/views/widget/desktop_aura/x11_whole_screen_move_loop.cc
index 3f48b8993b7e83b6f4a9ddd878f6a85951fbb4bb..782a9074ba9275e4a89f1aad9ccc32cb489e8034 100644
--- a/ui/views/widget/desktop_aura/x11_whole_screen_move_loop.cc
+++ b/ui/views/widget/desktop_aura/x11_whole_screen_move_loop.cc
@@ -8,6 +8,7 @@
 // Get rid of a macro from Xlib.h that conflicts with Aura's RootWindow class.
 #undef RootWindow
 
+#include "base/bind.h"
 #include "base/message_loop/message_loop.h"
 #include "base/message_loop/message_pump_x11.h"
 #include "base/run_loop.h"
@@ -31,6 +32,7 @@ namespace {
 // The minimum alpha before we declare a pixel transparent when searching in
 // our source image.
 const uint32 kMinAlpha = 32;
+const unsigned char kDragWidgetOpacity = 0xc0;
 
 class ScopedCapturer {
  public:
@@ -56,7 +58,9 @@ X11WholeScreenMoveLoop::X11WholeScreenMoveLoop(
     : delegate_(delegate),
       in_move_loop_(false),
       should_reset_mouse_flags_(false),
-      grab_input_window_(None) {
+      grab_input_window_(None),
+      motion_task_posted_(false) {
+  last_xmotion_.type = NoEventMask;
 }
 
 X11WholeScreenMoveLoop::~X11WholeScreenMoveLoop() {}
@@ -64,6 +68,16 @@ X11WholeScreenMoveLoop::~X11WholeScreenMoveLoop() {}
 ////////////////////////////////////////////////////////////////////////////////
 // DesktopWindowTreeHostLinux, MessagePumpDispatcher implementation:
 
+void X11WholeScreenMoveLoop::DispatchMouseMovement()

[sadrul, 2014/03/26 18:01:07]

{ EOL here

[varkha, 2014/03/27 04:48:13]

Done (moved to https://codereview.chromium.org/214113003/).

+{
+  if (!motion_task_posted_)
+    return;
+
+  motion_task_posted_ = false;
+  gfx::Point screen_point(last_xmotion_.x_root, last_xmotion_.y_root);
+  delegate_->OnMouseMovement(&last_xmotion_);
+}
+
 uint32_t X11WholeScreenMoveLoop::Dispatch(const base::NativeEvent& event) {
   XEvent* xev = event;
 
@@ -76,21 +90,34 @@ uint32_t X11WholeScreenMoveLoop::Dispatch(const base::NativeEvent& event) {
         gfx::Point location = gfx::ToFlooredPoint(
             screen->GetCursorScreenPoint() - drag_offset_);
         drag_widget_->SetBounds(gfx::Rect(location, drag_image_.size()));
+        drag_widget_->StackAtTop();
+      }
+      last_xmotion_ = xev->xmotion;

[sadrul, 2014/03/26 18:01:07]

Don't copy the whole event. Just keep track of the latest location in a
gfx::Point.

[varkha, 2014/03/27 04:48:13]

This was moved to https://codereview.chromium.org/214113003/. Please comment
there.

We need a NativeEvent& to pass to the delegate->OnMouseMovement. Do you think we
should assume that no other fields in the event are used (other than the time
and coordinates as used by DesktopDragDropClientAuraX11::OnMouseMovement.

+      if (!motion_task_posted_) {
+        gfx::Point screen_point(xev->xmotion.x_root, xev->xmotion.y_root);
+        motion_task_posted_ = true;
+        base::MessageLoopForUI::current()->PostTask(
+            FROM_HERE,
+            base::Bind(&X11WholeScreenMoveLoop::DispatchMouseMovement,
+                       base::Unretained(this)));

[sadrul, 2014/03/26 18:01:07]

You should use a WeakPtr<> here, instead of using Unretained(), and invalidate
the weak-ptr in EndMoveLoop().

You should also get rid of |motion_task_posted_|.

[varkha, 2014/03/27 04:48:13]

Will do in https://codereview.chromium.org/214113003/.

       }
-      delegate_->OnMouseMovement(&xev->xmotion);
       break;
     }
     case ButtonRelease: {
       if (xev->xbutton.button == Button1) {
         // Assume that drags are being done with the left mouse button. Only
         // break the drag if the left mouse button was released.
+        if (motion_task_posted_)
+          DispatchMouseMovement();
         delegate_->OnMouseReleased();
       }
       break;
     }
     case KeyPress: {
-      if (ui::KeyboardCodeFromXKeyEvent(xev) == ui::VKEY_ESCAPE)
+      if (ui::KeyboardCodeFromXKeyEvent(xev) == ui::VKEY_ESCAPE) {
+        motion_task_posted_ = false;
         EndMoveLoop();
+      }
       break;
     }
   }
@@ -267,6 +294,7 @@ void X11WholeScreenMoveLoop::CreateDragImageWindow() {
   widget->set_focus_on_creation(false);
   widget->set_frame_type(Widget::FRAME_TYPE_FORCE_NATIVE);
   widget->Init(params);
+  widget->SetOpacity(kDragWidgetOpacity);
   widget->GetNativeWindow()->SetName("DragWindow");
 
   ImageView* image = new ImageView();