Revert 162381 - linux_aura: Fix tab dragging performance.

ui/aura/root_window_host_linux.cc

Index: ui/aura/root_window_host_linux.cc
===================================================================
--- ui/aura/root_window_host_linux.cc	(revision 162390)
+++ ui/aura/root_window_host_linux.cc	(working copy)
@@ -31,7 +31,6 @@
 #include "ui/base/ui_base_switches.h"
 #include "ui/base/view_prop.h"
 #include "ui/base/x/valuators.h"
-#include "ui/base/x/x11_util.h"
 #include "ui/compositor/dip_util.h"
 #include "ui/compositor/layer.h"
 #include "ui/gfx/codec/png_codec.h"
@@ -75,6 +74,91 @@
   return target;
 }
 
+// Coalesce all pending motion events (touch or mouse) that are at the top of
+// the queue, and return the number eliminated, storing the last one in
+// |last_event|.
+int CoalescePendingMotionEvents(const XEvent* xev, XEvent* last_event) {
+  XIDeviceEvent* xievent = static_cast<XIDeviceEvent*>(xev->xcookie.data);
+  int num_coalesed = 0;
+  Display* display = xev->xany.display;
+  int event_type = xev->xgeneric.evtype;
+
+#if defined(USE_XI2_MT)
+  float tracking_id = -1;
+  if (event_type == XI_TouchUpdate) {
+    if (!ui::ValuatorTracker::GetInstance()->ExtractValuator(*xev,
+          ui::ValuatorTracker::VAL_TRACKING_ID, &tracking_id))
+      tracking_id = -1;
+  }
+#endif
+
+  while (XPending(display)) {
+    XEvent next_event;
+    XPeekEvent(display, &next_event);
+
+    // If we can't get the cookie, abort the check.
+    if (!XGetEventData(next_event.xgeneric.display, &next_event.xcookie))
+      return num_coalesed;
+
+    // If this isn't from a valid device, throw the event away, as
+    // that's what the message pump would do. Device events come in pairs
+    // with one from the master and one from the slave so there will
+    // always be at least one pending.
+    if (!ui::TouchFactory::GetInstance()->ShouldProcessXI2Event(&next_event)) {
+      XFreeEventData(display, &next_event.xcookie);
+      XNextEvent(display, &next_event);
+      continue;
+    }
+
+    if (next_event.type == GenericEvent &&
+        next_event.xgeneric.evtype == event_type &&
+        !ui::GetScrollOffsets(&next_event, NULL, NULL)) {
+      XIDeviceEvent* next_xievent =
+          static_cast<XIDeviceEvent*>(next_event.xcookie.data);
+#if defined(USE_XI2_MT)
+      float next_tracking_id = -1;
+      if (event_type == XI_TouchUpdate) {
+        // If this is a touch motion event (as opposed to mouse motion event),
+        // then make sure the events are from the same touch-point.
+        if (!ui::ValuatorTracker::GetInstance()->ExtractValuator(next_event,
+              ui::ValuatorTracker::VAL_TRACKING_ID, &next_tracking_id))
+          next_tracking_id = -1;
+      }
+#endif
+      // Confirm that the motion event is targeted at the same window
+      // and that no buttons or modifiers have changed.
+      if (xievent->event == next_xievent->event &&
+          xievent->child == next_xievent->child &&
+#if defined(USE_XI2_MT)
+          (event_type == XI_Motion || tracking_id == next_tracking_id) &&
+#endif
+          xievent->buttons.mask_len == next_xievent->buttons.mask_len &&
+          (memcmp(xievent->buttons.mask,
+                  next_xievent->buttons.mask,
+                  xievent->buttons.mask_len) == 0) &&
+          xievent->mods.base == next_xievent->mods.base &&
+          xievent->mods.latched == next_xievent->mods.latched &&
+          xievent->mods.locked == next_xievent->mods.locked &&
+          xievent->mods.effective == next_xievent->mods.effective) {
+        XFreeEventData(display, &next_event.xcookie);
+        // Free the previous cookie.
+        if (num_coalesed > 0)
+          XFreeEventData(display, &last_event->xcookie);
+        // Get the event and its cookie data.
+        XNextEvent(display, last_event);
+        XGetEventData(display, &last_event->xcookie);
+        ++num_coalesed;
+        continue;
+      } else {
+        // This isn't an event we want so free its cookie data.
+        XFreeEventData(display, &next_event.xcookie);
+      }
+    }
+    break;
+  }
+  return num_coalesed;
+}
+
 void SelectEventsForRootWindow() {
   Display* display = ui::GetXDisplay();
   ::Window root_window = ui::GetX11RootWindow();
@@ -461,7 +545,7 @@
 
   switch (type) {
     case ui::ET_TOUCH_MOVED:
-      num_coalesced = ui::CoalescePendingMotionEvents(xev, &last_event);
+      num_coalesced = CoalescePendingMotionEvents(xev, &last_event);
       if (num_coalesced > 0)
         xev = &last_event;
       // fallthrough
@@ -500,7 +584,7 @@
       if (type == ui::ET_MOUSE_MOVED || type == ui::ET_MOUSE_DRAGGED) {
         // If this is a motion event, we want to coalesce all pending motion
         // events that are at the top of the queue.
-        num_coalesced = ui::CoalescePendingMotionEvents(xev, &last_event);
+        num_coalesced = CoalescePendingMotionEvents(xev, &last_event);
         if (num_coalesced > 0)
           xev = &last_event;
       } else if (type == ui::ET_MOUSE_PRESSED) {