Use XGrabPointer instead of XChangeActivatePointerGrab() to change the cursor during a pointer grab

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 cf259d3598a309f17f3158631290344da345568f..ea2d5c65a4fe786d1b3918e1aeee0dc84d78d143 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
@@ -21,6 +21,7 @@
 #include "ui/events/keycodes/keyboard_code_conversion_x.h"
 #include "ui/events/platform/scoped_event_dispatcher.h"
 #include "ui/events/platform/x11/x11_event_source.h"
+#include "ui/views/widget/desktop_aura/x11_pointer_grab.h"
 
 namespace views {
 
@@ -39,7 +40,6 @@ const unsigned int kModifiersMasks[] = {
 X11WholeScreenMoveLoop::X11WholeScreenMoveLoop(X11MoveLoopDelegate* delegate)
     : delegate_(delegate),
       in_move_loop_(false),
-      initial_cursor_(ui::kCursorNull),
       should_reset_mouse_flags_(false),
       grab_input_window_(None),
       grabbed_pointer_(false),
@@ -123,14 +123,9 @@ uint32_t X11WholeScreenMoveLoop::DispatchEvent(const ui::PlatformEvent& event) {
   return ui::POST_DISPATCH_PERFORM_DEFAULT;
 }
 
-bool X11WholeScreenMoveLoop::RunMoveLoop(aura::Window* source,
-                                         gfx::NativeCursor cursor) {
+bool X11WholeScreenMoveLoop::RunMoveLoop(aura::Window* source) {
   DCHECK(!in_move_loop_);  // Can only handle one nested loop at a time.
 
-  // Query the mouse cursor prior to the move loop starting so that it can be
-  // restored when the move loop finishes.
-  initial_cursor_ = source->GetHost()->last_cursor();
-
   grab_input_window_ = CreateDragInputWindow(gfx::GetXDisplay());
 
   // Only grab mouse capture of |grab_input_window_| if |source| does not have
@@ -145,7 +140,7 @@ bool X11WholeScreenMoveLoop::RunMoveLoop(aura::Window* source,
     aura::client::CaptureClient* capture_client =
         aura::client::GetCaptureClient(source->GetRootWindow());
     CHECK(capture_client->GetGlobalCaptureWindow() == NULL);
-    grabbed_pointer_ = GrabPointer(cursor);
+    grabbed_pointer_ = GrabPointer();
     if (!grabbed_pointer_) {
       XDestroyWindow(gfx::GetXDisplay(), grab_input_window_);
       return false;
@@ -187,13 +182,12 @@ bool X11WholeScreenMoveLoop::RunMoveLoop(aura::Window* source,
 
 void X11WholeScreenMoveLoop::UpdateCursor(gfx::NativeCursor cursor) {
   if (in_move_loop_) {
-    // We cannot call GrabPointer() because we do not want to change the
-    // "owner_events" property of the active pointer grab.
-    XChangeActivePointerGrab(
-        gfx::GetXDisplay(),
-        ButtonPressMask | ButtonReleaseMask | PointerMotionMask,
-        cursor.platform(),
-        CurrentTime);
+    if (grabbed_pointer_) {
+      // Do not grab the server. We already have pointer grab.
+      ::views::GrabPointer(grab_input_window_, false, cursor.platform());
+    } else {
+      NOTREACHED();

[sadrul, 2015/01/15 23:41:20]

Add a comment like so:

  NOTREACHED() << "You must call RunMoveLoop() and check its return value
first.";

[pkotwicz, 2015/01/16 15:22:46]

This message would be incorrect. We reach here if the move loop is active, but
the aura::Window passed in to RunMoveLoop() already had capture.

RunMoveLoop() is blocking so you only get the return value when the move loop
has ended...

[sadrul, 2015/01/16 15:25:14]

The point is, add a correct comment that explains the failure, so the developer
knows what to do to fix it.

+    }
   }
 }
 
@@ -215,12 +209,10 @@ void X11WholeScreenMoveLoop::EndMoveLoop() {
   // the chrome process.
 
   // Ungrab before we let go of the window.
-  XDisplay* display = gfx::GetXDisplay();
   if (grabbed_pointer_)
-    XUngrabPointer(display, CurrentTime);
-  else
-    UpdateCursor(initial_cursor_);
+    UngrabPointer();
 
+  XDisplay* display = gfx::GetXDisplay();
   unsigned int esc_keycode = XKeysymToKeycode(display, XK_Escape);
   for (size_t i = 0; i < arraysize(kModifiersMasks); ++i) {
     XUngrabKey(display, esc_keycode, kModifiersMasks[i], grab_input_window_);
@@ -236,22 +228,13 @@ void X11WholeScreenMoveLoop::EndMoveLoop() {
   quit_closure_.Run();
 }
 
-bool X11WholeScreenMoveLoop::GrabPointer(gfx::NativeCursor cursor) {
+bool X11WholeScreenMoveLoop::GrabPointer() {
   XDisplay* display = gfx::GetXDisplay();
   XGrabServer(display);
 
   // Pass "owner_events" as false so that X sends all mouse events to
   // |grab_input_window_|.
-  int ret = XGrabPointer(
-      display,
-      grab_input_window_,
-      False,  // owner_events
-      ButtonPressMask | ButtonReleaseMask | PointerMotionMask,
-      GrabModeAsync,
-      GrabModeAsync,
-      None,
-      cursor.platform(),
-      CurrentTime);
+  int ret = ::views::GrabPointer(grab_input_window_, false, None);
   if (ret != GrabSuccess) {
     DLOG(ERROR) << "Grabbing pointer for dragging failed: "
                 << ui::GetX11ErrorString(display, ret);