Set plugin focus via element dispatch

third_party/WebKit/Source/core/html/HTMLPlugInElement.cpp

Index: third_party/WebKit/Source/core/html/HTMLPlugInElement.cpp
diff --git a/third_party/WebKit/Source/core/html/HTMLPlugInElement.cpp b/third_party/WebKit/Source/core/html/HTMLPlugInElement.cpp
index d90cb6f799e9e99214dd862bc71954a047db59f9..895b44d1ffd7e832ef03c0cbbcec185101751649 100644
--- a/third_party/WebKit/Source/core/html/HTMLPlugInElement.cpp
+++ b/third_party/WebKit/Source/core/html/HTMLPlugInElement.cpp
@@ -97,6 +97,24 @@ DEFINE_TRACE(HTMLPlugInElement) {
   HTMLFrameOwnerElement::trace(visitor);
 }
 
+void HTMLPlugInElement::dispatchBlurEvent(
+    Element* newFocusedElement,
+    WebFocusType type,
+    InputDeviceCapabilities* sourceCapabilities) {
+  Element::dispatchBlurEvent(newFocusedElement, type, sourceCapabilities);

[haraken, 2017/04/06 06:20:26]

Can we add a comment on why we want to call Element::dispatchBlurEvent first?

[joelhockey, 2017/04/06 06:28:39]

Done.  I hope my explanation is reasonable.  Feel free to suggest something
else.

[dcheng, 2017/04/06 06:28:49]

Thinking about this more, either ordering makes me nervous.

1) If we do the plugin first, and the plugin changes focus, we may
double-dispatch this blur event.

2) However, if we dispatch the DOM event first and the DOM event refocuses this
plugin, we will re-enter Document::setFocusedElement. I think this means we can
end up with plugin focus state in an inconsistent state: setFocused() will be
false on the plugin, since this runs after the re-entrant focus change.

In my mind, the safer alternative is to just have Document::setFocusedElement()
call this directly on the plugin (by checking if the focused element is a plugin
element and downcasting if so). What do you think of just doing this and not
using the override? This also lets us keep the original ordering of events.

[joelhockey, 2017/04/07 06:56:05]

You are right that it was possible for plugin to end up in an inconsistent
state. 

+  if (m_plugin)
+    m_plugin->setFocused(false, type);
+}
+
+void HTMLPlugInElement::dispatchFocusEvent(
+    Element* oldFocusedElement,
+    WebFocusType type,
+    InputDeviceCapabilities* sourceCapabilities) {
+  Element::dispatchFocusEvent(oldFocusedElement, type, sourceCapabilities);
+  if (m_plugin)
+    m_plugin->setFocused(true, type);
+}
+
 void HTMLPlugInElement::setPlugin(PluginView* plugin) {
   if (plugin == m_plugin)
     return;