Add PlatformWindow/Event related code for Ozone X11.

ui/events/platform/x11/x11_event_source.h

Index: ui/events/platform/x11/x11_event_source.h
diff --git a/ui/events/platform/x11/x11_event_source.h b/ui/events/platform/x11/x11_event_source.h
index 26d646016607273684183310df1a393d8e0d1558..472e89e1a3a8dd5e905c0eb57f2f419194a0c154 100644
--- a/ui/events/platform/x11/x11_event_source.h
+++ b/ui/events/platform/x11/x11_event_source.h
@@ -9,6 +9,7 @@
 
 #include "base/macros.h"
 #include "base/memory/scoped_ptr.h"
+#include "base/observer_list.h"
 #include "ui/events/events_export.h"
 #include "ui/events/platform/platform_event_source.h"
 #include "ui/gfx/x/x11_types.h"
@@ -20,6 +21,20 @@ typedef unsigned long XID;
 
 namespace ui {
 
+// Interface for classes that want to receive XEvent directly. Only used with
+// ozone_platform_x11 and only events that can't be translated into ui::Events
+// are sent via this path.
+class EVENTS_EXPORT XEventDispatcher {
+ public:
+  // Sends XEvent to XEventDispatcher for handling. Returns true if the XEvent
+  // was dispatched, otherwise false. After the first XEventDispatcher returns
+  // true XEvent dispatching stops.
+  virtual bool DispatchXEvent(const XEvent& event) = 0;
+
+ protected:
+  virtual ~XEventDispatcher() {}
+};
+
 class X11HotplugEventHandler;
 
 // A PlatformEventSource implementation for reading events from X11 server and
@@ -31,6 +46,12 @@ class EVENTS_EXPORT X11EventSource : public PlatformEventSource {
 
   static X11EventSource* GetInstance();
 
+  // Adds a XEvent dispatcher to the dispatcher list.
+  void AddXEventDispatcher(XEventDispatcher* dispatcher);
+
+  // Removes a XEvent dispatcher from the dispatcher list.
+  void RemoveXEventDispatcher(XEventDispatcher* dispatcher);
+
   // Called by the glib source dispatch function. Processes all (if any)
   // available X events.
   void DispatchXEvents();
@@ -56,10 +77,16 @@ class EVENTS_EXPORT X11EventSource : public PlatformEventSource {
   uint32_t ExtractCookieDataDispatchEvent(XEvent* xevent);
 
   // PlatformEventSource:
-  uint32_t DispatchEvent(XEvent* xevent) override;
+  uint32_t DispatchEvent(base::NativeEvent native_event) override;
   void StopCurrentEventStream() override;
   void OnDispatcherListChanged() override;
 
+  // Sends XEvent to registered XEventDispatchers.
+  void DispatchXEventToXEventDispatchers(XEvent* xevent);
+
+  // Handles updates after event has been dispatched.
+  void PostDispatchEvent(XEvent* xevent);
+
   // The connection to the X11 server used to receive the events.
   XDisplay* display_;
 
@@ -69,6 +96,10 @@ class EVENTS_EXPORT X11EventSource : public PlatformEventSource {
 
   scoped_ptr<X11HotplugEventHandler> hotplug_event_handler_;
 
+  // Keep track of all XEventDispatcher to send XEvents directly to, only used
+  // with ozone.

[spang, 2016/01/26 21:37:40]

Why "only used with ozone" ?

I think anything that would be plumbed through this on ozone could do so on
cros-x11 & desktop as well. Then you won't need any ifdef in the GLX code, for
example.

[kylechar, 2016/01/27 15:39:26]

As long as there are no PlatformEventObservers in USE_X11 that care about that
type of event (which doesn't appear to be the case) that would totally work and
make things simpler. It might be a little weird though because PlatformEvent is
also an XEvent in USE_X11 build.

[kylechar, 2016/02/01 16:44:27]

After talking with Sadrul we decided that only X11EventSourceOzone will maintain
a list of XEventDispatchers.

+  base::ObserverList<XEventDispatcher> x_dispatchers_;
+
   DISALLOW_COPY_AND_ASSIGN(X11EventSource);
 };