Require a mouse button release event before counting a press event as a new click.

ui/events/event.cc

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "ui/events/event.h"
 
 #if defined(USE_X11)
 #include <X11/extensions/XInput2.h>
 #include <X11/Xlib.h>
 #endif
@@ skipping 299 matching lines @@
   if (std::abs(event2.y() - event1.y()) > kDoubleClickHeight / 2)
     return false;
 
   return true;
 }
 
 // static
 int MouseEvent::GetRepeatCount(const MouseEvent& event) {
   int click_count = 1;
   if (last_click_event_) {
-    if (event.type() == ui::ET_MOUSE_RELEASED)
-      return last_click_event_->GetClickCount();
-    if (IsX11SendEventTrue(event.native_event()))
+    if (event.type() == ui::ET_MOUSE_RELEASED) {
+      if (event.changed_button_flags() ==
+              last_click_event_->changed_button_flags()) {
+        last_click_complete_ = true;
+        return last_click_event_->GetClickCount();
+      } else {
+        // If last_click_event_ has changed since this button was pressed
+        // return a click count of 1.
+        return click_count;
+      }
+    }
+    if (event.time_stamp() != last_click_event_->time_stamp())
+      last_click_complete_ = true;
+    if (!last_click_complete_ ||
+        IsX11SendEventTrue(event.native_event())) {
       click_count = last_click_event_->GetClickCount();
-    else if (IsRepeatedClickEvent(*last_click_event_, event))
+    } else if (IsRepeatedClickEvent(*last_click_event_, event)) {
       click_count = last_click_event_->GetClickCount() + 1;
+    }
     delete last_click_event_;
   }
   last_click_event_ = new MouseEvent(event);
+  last_click_complete_ = false;

[sky, 2014/07/18 22:42:51]

Do we need both last_click_complete_ and last_click_event_? When complete could
you delete and NULL out last_click_event_ instead of maintaining both?

[flackr, 2014/07/19 12:55:11]

It's marked complete when another pressed event should be considered as a new
unique press, at which point we can use last_click_event_ to determine if they
were close together enough to increase the click count. If we NULL'd out
last_click_event_ we would lose the click count and wouldn't be able to double
click.

I was also considering whether just checking that the timestamps of the pressed
events were different but I'm not sure if we might have low precision timestamps
on some OS's such that the two presses in a double click would have the same
timestamp.

   if (click_count > 3)
     click_count = 3;
   last_click_event_->SetClickCount(click_count);
   return click_count;
 }
 
+void MouseEvent::ResetLastClickForTest() {
+  if (last_click_event_) {
+    delete last_click_event_;
+    last_click_event_ = NULL;
+    last_click_complete_ = false;
+  }
+}
+
 // static
 MouseEvent* MouseEvent::last_click_event_ = NULL;
+bool MouseEvent::last_click_complete_ = false;
 
 int MouseEvent::GetClickCount() const {
   if (type() != ET_MOUSE_PRESSED && type() != ET_MOUSE_RELEASED)
     return 0;
 
   if (flags() & EF_IS_TRIPLE_CLICK)
     return 3;
   else if (flags() & EF_IS_DOUBLE_CLICK)
     return 2;
   else
@@ skipping 402 matching lines @@
                    gfx::PointF(x, y),
                    time_stamp,
                    flags | EF_FROM_TOUCH),
       details_(details) {
 }
 
 GestureEvent::~GestureEvent() {
 }
 
 }  // namespace ui