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

ui/events/event.h

Index: ui/events/event.h
diff --git a/ui/events/event.h b/ui/events/event.h
index 2988d471b11c1060fc2a49a896d672d52babce44..58cccbbada6e1bec906066e0baab345a59982464 100644
--- a/ui/events/event.h
+++ b/ui/events/event.h
@@ -8,6 +8,7 @@
 #include "base/basictypes.h"
 #include "base/compiler_specific.h"
 #include "base/event_types.h"
+#include "base/gtest_prod_util.h"
 #include "base/logging.h"
 #include "base/time/time.h"
 #include "ui/events/event_constants.h"
@@ -397,6 +398,8 @@ class EVENTS_EXPORT MouseEvent : public LocatedEvent {
   void set_changed_button_flags(int flags) { changed_button_flags_ = flags; }
 
  private:
+  FRIEND_TEST_ALL_PREFIXES(EventTest, DoubleClickRequiresRelease);
+
   // Returns the repeat count based on the previous mouse click, if it is
   // recent enough and within a small enough distance.
   static int GetRepeatCount(const MouseEvent& click_event);
@@ -405,6 +408,7 @@ class EVENTS_EXPORT MouseEvent : public LocatedEvent {
   int changed_button_flags_;
 
   static MouseEvent* last_click_event_;
+  static bool last_click_released_;
 };
 
 class ScrollEvent;