This fixes http://code.google.com/p/chromium/issues/detail?id=3007, which is ...

webkit/tools/test_shell/event_sending_controller.cc

Index: webkit/tools/test_shell/event_sending_controller.cc
===================================================================
--- webkit/tools/test_shell/event_sending_controller.cc	(revision 2916)
+++ webkit/tools/test_shell/event_sending_controller.cc	(working copy)
@@ -35,6 +35,8 @@
 WebMouseEvent::Button EventSendingController::pressed_button_ = 
     WebMouseEvent::BUTTON_NONE;
 
+int EventSendingController::last_button_number_ = -1;
+
 namespace {
 
 #if defined(OS_WIN)
@@ -149,6 +151,7 @@
   dragMode.Set(true);
   last_click_time_sec = 0;
   click_count = 0;
+  last_button_number_ = -1;
 }
 
 /* static */ WebView* EventSendingController::webview() {
@@ -170,19 +173,27 @@
 }
 #endif
 
+WebMouseEvent::Button EventSendingController::GetButtonTypeFromButtonNumber(
+    int button_code) {
+  if (button_code == 0)
+    return WebMouseEvent::BUTTON_LEFT;
+  else if (button_code == 2)
+    return WebMouseEvent::BUTTON_RIGHT;
+
+  return WebMouseEvent::BUTTON_MIDDLE;
+}
+
 // static
-WebMouseEvent::Button EventSendingController::GetButtonTypeFromSingleArg(
+int EventSendingController::GetButtonNumberFromSingleArg(
     const CppArgumentList& args) {
+  int button_code = 0;
+
   if (args.size() > 0 && args[0].isNumber()) {
-    int button_code = args[0].ToInt32();
-    if (button_code == 1)
-      return WebMouseEvent::BUTTON_MIDDLE;
-    else if (button_code == 2)
-      return WebMouseEvent::BUTTON_RIGHT;
+    button_code = args[0].ToInt32();
   }
-  return WebMouseEvent::BUTTON_LEFT;
+
+  return button_code;
 }
-
 //
 // Implemented javascript methods.
 //
@@ -193,15 +204,22 @@
 
   webview()->Layout();
 
-  WebMouseEvent::Button button_type = GetButtonTypeFromSingleArg(args);
+  int button_number = GetButtonNumberFromSingleArg(args);
+  DCHECK(button_number != -1);
 
-  if ((GetCurrentEventTimeSec() - last_click_time_sec >= kMultiClickTimeSec) ||
-      outside_multiclick_radius(last_mouse_pos_, last_click_pos)) {
+  WebMouseEvent::Button button_type = GetButtonTypeFromButtonNumber(
+      button_number);
+
+  if ((GetCurrentEventTimeSec() - last_click_time_sec < kMultiClickTimeSec) &&
+      (!outside_multiclick_radius(last_mouse_pos_, last_click_pos)) &&
+      (button_number == last_button_number_)) {
+    ++click_count;
+  } else {
     click_count = 1;
-  } else {
-    ++click_count;
   }
 
+  last_button_number_ = button_number;
+
   WebMouseEvent event;
   pressed_button_ = button_type;
   InitMouseEvent(WebInputEvent::MOUSE_DOWN, button_type,
@@ -215,8 +233,14 @@
 
   webview()->Layout();
 
-  WebMouseEvent::Button button_type = GetButtonTypeFromSingleArg(args);
+  int button_number = GetButtonNumberFromSingleArg(args);
+  DCHECK(button_number != -1);
 
+  WebMouseEvent::Button button_type = GetButtonTypeFromButtonNumber(
+      button_number);
+
+  last_button_number_ = button_number;
+
   WebMouseEvent event;
   InitMouseEvent(WebInputEvent::MOUSE_UP, button_type,
                  last_mouse_pos_, &event);