Turn MoveLeave event sending into a feature for testing enabling it.

Don't change the current implementation but enable the ability to
adjust the mouse leave event sending dynamically.

BUG=450631

Review-Url: https://codereview.chromium.org/2614163002
Cr-Commit-Position: refs/heads/master@{#442025}

ui/events/blink/blink_features.cc

@@ -11,4 +11,14 @@ namespace features {
 const base::Feature kVsyncAlignedInputEvents{"VsyncAlignedInput",
                                              base::FEATURE_DISABLED_BY_DEFAULT};
 
+const base::Feature kSendMouseLeaveEvents {
+  "SendMouseLeaveEvents",
+// TODO(chaopeng) this fix only for chromeos now, should convert ET_MOUSE_EXITED
+// to MouseLeave when crbug.com/450631 fixed.
+#if defined(OS_CHROMEOS)
+      base::FEATURE_ENABLED_BY_DEFAULT
+#else
+      base::FEATURE_DISABLED_BY_DEFAULT
+#endif
+};
 }

ui/events/blink/blink_features.h

@@ -11,6 +11,11 @@ namespace features {
 
 extern const base::Feature kVsyncAlignedInputEvents;
 
+// This feature allows native ET_MOUSE_EXIT events to be passed
+// through to blink as mouse leave events. Traditionally these events were
+// converted to mouse move events due to a number of incosistencies on
+// the native platforms. Enabled by default on ChromeOS. crbug.com/450631
+extern const base::Feature kSendMouseLeaveEvents;
 }
 
 #endif  // UI_EVENTS_BLINK_BLINK_FEATURES_H_

ui/events/blink/web_input_event.cc

@@ -6,6 +6,7 @@
 
 #include "ui/events/base_event_utils.h"
 #include "ui/events/blink/blink_event_util.h"
+#include "ui/events/blink/blink_features.h"
 #include "ui/events/event.h"
 #include "ui/events/event_utils.h"
 #include "ui/events/keycodes/dom/keycode_converter.h"
@@ -385,13 +386,13 @@ blink::WebMouseEvent MakeWebMouseEventFromUiEvent(const MouseEvent& event) {
       type = blink::WebInputEvent::MouseUp;
       click_count = event.GetClickCount();
       break;
-    case ET_MOUSE_EXITED:
-// TODO(chaopeng) this fix only for chromeos now, should convert ET_MOUSE_EXITED
-// to MouseLeave when crbug.com/450631 fixed.
-#if defined(OS_CHROMEOS)
-      type = blink::WebInputEvent::MouseLeave;
+    case ET_MOUSE_EXITED: {
+      static bool s_send_leave =
+          base::FeatureList::IsEnabled(features::kSendMouseLeaveEvents);
+      type = s_send_leave ? blink::WebInputEvent::MouseLeave
+                          : blink::WebInputEvent::MouseMove;
       break;
-#endif
+    }
     case ET_MOUSE_ENTERED:
     case ET_MOUSE_MOVED:
     case ET_MOUSE_DRAGGED: