Fix a UMR that happens while trying to forward mouse events.

chrome/browser/renderer_host/render_view_host.cc

Index: chrome/browser/renderer_host/render_view_host.cc
diff --git a/chrome/browser/renderer_host/render_view_host.cc b/chrome/browser/renderer_host/render_view_host.cc
index d7d787e6e78f22364d88d987e6de64e07949cd23..2fde17ffd73119a39699ebda17a74a0994eec24c 100644
--- a/chrome/browser/renderer_host/render_view_host.cc
+++ b/chrome/browser/renderer_host/render_view_host.cc
@@ -1411,11 +1411,14 @@ gfx::Rect RenderViewHost::GetRootWindowResizerRect() const {
 
 void RenderViewHost::ForwardMouseEvent(
     const WebKit::WebMouseEvent& mouse_event) {
-  RenderWidgetHost::ForwardMouseEvent(mouse_event);
+  // We make a copy of the mouse event because
+  // RenderWidgetHost::ForwardMouseEvent will delete |mouse_event|.
+  WebKit::WebMouseEvent event_copy(mouse_event);
+  RenderWidgetHost::ForwardMouseEvent(event_copy);
 
   RenderViewHostDelegate::View* view = delegate_->GetViewDelegate();
   if (view) {
-    switch (mouse_event.type) {
+    switch (event_copy.type) {
       case WebInputEvent::MouseMove:
         view->HandleMouseEvent();
         break;