events: Update mouse-event handlers to not return EventResult.

content/browser/web_contents/web_contents_view_aura.cc

Index: content/browser/web_contents/web_contents_view_aura.cc
diff --git a/content/browser/web_contents/web_contents_view_aura.cc b/content/browser/web_contents/web_contents_view_aura.cc
index c31128b65d3cc8774a0d5ab2d5b6d1a26311a180..e06038324b5e9c0ba3b0e09d5fdc1ed8047a37f8 100644
--- a/content/browser/web_contents/web_contents_view_aura.cc
+++ b/content/browser/web_contents/web_contents_view_aura.cc
@@ -911,9 +911,9 @@ scoped_refptr<ui::Texture> WebContentsViewAura::CopyTexture() {
 void WebContentsViewAura::OnKeyEvent(ui::KeyEvent* event) {
 }
 
-ui::EventResult WebContentsViewAura::OnMouseEvent(ui::MouseEvent* event) {
+void WebContentsViewAura::OnMouseEvent(ui::MouseEvent* event) {
   if (!web_contents_->GetDelegate())
-    return ui::ER_UNHANDLED;
+    return;
 
   switch (event->type()) {
     case ui::ET_MOUSE_PRESSED:
@@ -928,7 +928,6 @@ ui::EventResult WebContentsViewAura::OnMouseEvent(ui::MouseEvent* event) {
     default:
       break;
   }
-  return ui::ER_UNHANDLED;
 }
 
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