Fix grabbing capture when the mouse is pressed on Desktop Linux.

ui/base/x/x11_util.cc

Index: ui/base/x/x11_util.cc
diff --git a/ui/base/x/x11_util.cc b/ui/base/x/x11_util.cc
index 03625c6de02f0782c1b8d3861f447c156daa0377..d61c5f9bc882e790e2b24cb2001453fbbadcf1dc 100644
--- a/ui/base/x/x11_util.cc
+++ b/ui/base/x/x11_util.cc
@@ -284,6 +284,51 @@ bool IsXInput2Available() {
   return DeviceDataManagerX11::GetInstance()->IsXInput2Available();
 }
 
+int GrabPointer(XID window, bool owner_events, ::Cursor cursor) {
+  if (IsXInput2Available()) {
+    // Do an XINPUT2 pointer grab. If there is an active XINPUT2 pointer grab
+    // as a result of normal button press, XGrabPointer() will fail.
+    const std::vector<int>& master_pointers =
+        DeviceDataManagerX11::GetInstance()->master_pointers();
+    int success = GrabSuccess;
+    for (size_t i = 0; i < master_pointers.size(); ++i) {
+      unsigned char mask[XIMaskLen(XI_LASTEVENT)];
+      memset(mask, 0, sizeof(mask));
+      XISetMask(mask, XI_ButtonPress);
+      XISetMask(mask, XI_ButtonRelease);
+      XISetMask(mask, XI_Motion);
+      XIEventMask evmask;
+      evmask.deviceid = XIAllDevices;

[sadrul, 2014/12/22 21:08:59]

Should you use master_pointers[i] here?

[pkotwicz, 2014/12/23 00:29:49]

It seems to work either way. I haven't seen any documentation as to which way is
"right".

+      evmask.mask_len = sizeof(mask);
+      evmask.mask = mask;
+      success = XIGrabDevice(gfx::GetXDisplay(), master_pointers[i], window,
+                             CurrentTime, cursor, GrabModeAsync, GrabModeAsync,
+                             owner_events, &evmask);
+      // Assume that the grab will succeed on either all or none of the master
+      // pointers.
+      if (success != GrabSuccess)
+        return success;
+    }
+    return success;
+  } else {

[pkotwicz, 2014/12/01 22:42:48]

Should I try XGrabPointer() if XIGrabDevice() fails?

[sadrul, 2014/12/22 21:08:59]

Sure. Let's try that.

Also, remove else.

[pkotwicz, 2014/12/23 00:29:49]

Done.

+    int event_mask = PointerMotionMask | ButtonReleaseMask | ButtonPressMask;
+    return XGrabPointer(gfx::GetXDisplay(), window, owner_events, event_mask,
+                        GrabModeAsync, GrabModeAsync, None,
+                        cursor, CurrentTime);
+  }
+}
+
+void UngrabPointer() {
+  if (IsXInput2Available()) {
+    const std::vector<int>& master_pointers =
+        DeviceDataManagerX11::GetInstance()->master_pointers();
+    for (size_t i = 0; i < master_pointers.size(); ++i)
+      XIUngrabDevice(gfx::GetXDisplay(), master_pointers[i], CurrentTime);
+  } else {
+    XUngrabPointer(gfx::GetXDisplay(), CurrentTime);
+  }
+}
+
 static SharedMemorySupport DoQuerySharedMemorySupport(XDisplay* dpy) {
   int dummy;
   Bool pixmaps_supported;