X11: Add window cache

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 927e67d803e6bae145f6150498b8ae9380016f82..cfa43914ecfe3c230b989910a994d839ca8cbef3 100644
--- a/ui/events/platform/x11/x11_event_source.h
+++ b/ui/events/platform/x11/x11_event_source.h
@@ -6,11 +6,15 @@
 #define UI_EVENTS_PLATFORM_X11_X11_EVENT_SOURCE_H_
 
 #include <stdint.h>
+#include <xcb/xcb.h>
 
+#include <list>
 #include <memory>
+#include <queue>
 #include <stack>
 
 #include "base/macros.h"
+#include "base/memory/weak_ptr.h"
 #include "base/optional.h"
 #include "ui/events/events_export.h"
 #include "ui/gfx/x/x11_types.h"
@@ -47,6 +51,32 @@ class X11EventSourceDelegate {
 // receiving, pre-process and post-processing XEvents.
 class EVENTS_EXPORT X11EventSource {
  public:
+  class EVENTS_EXPORT Request {
+   public:
+    ~Request();
+
+    virtual void OnReply(xcb_generic_reply_t* reply,
+                         xcb_generic_error_t* error) = 0;
+
+    uint32_t sequence() { return sequence_; }
+
+    base::WeakPtr<Request> GetWeakPtr();
+
+   protected:
+    Request(uint32_t sequence);
+
+    uint32_t sequence_;
+
+    // State necessary for discarding.  Set during
+    // X11EventSource::EnqueueRequest.
+    std::list<std::unique_ptr<Request>>::iterator it_;
+
+    base::WeakPtrFactory<Request> weak_factory_;
+
+   private:
+    friend class X11EventSource;
+  };
+
   X11EventSource(X11EventSourceDelegate* delegate, XDisplay* display);
   ~X11EventSource();
 
@@ -87,6 +117,16 @@ class EVENTS_EXPORT X11EventSource {
   // dispatched that contains that information.
   base::Optional<gfx::Point> GetRootCursorLocationFromCurrentEvent() const;
 
+  // Takes ownership of |request|.
+  void EnqueueRequest(Request* request);
+
+  void DiscardRequest(Request* request);
+
+  // Blocks until the reply corresponding to |request| is available.  Dispatches
+  // the request in a nested-message-loop fashion.  Returns true iff the request
+  // resulted in an error.
+  bool DispatchRequestNow(Request* request);
+
   void StopCurrentEventStream();
   void OnDispatcherListChanged();
 
@@ -107,13 +147,26 @@ class EVENTS_EXPORT X11EventSource {
   // |last_seen_server_time_| with this value.
   Time GetCurrentServerTime();
 
+  bool HasNextReply();
+  uint32_t NextReplySequence();
+  void ProcessRequest(Request* request,
+                      xcb_generic_reply_t* reply,
+                      xcb_generic_error_t* error);
+  void ProcessNextReply();
+
+  bool HasNextEvent();
+  uint32_t NextEventSequence();
+  void ProcessNextEvent();
+
  private:
+  friend class TestX11EventSource;
   static X11EventSource* instance_;
 
   X11EventSourceDelegate* delegate_;
 
   // The connection to the X11 server used to receive the events.
   XDisplay* display_;
+  xcb_connection_t* connection_;
 
   // Events currently being dispatched.  The topmost event in this stack
   // corresponds to the deepest-nested message loop.
@@ -125,6 +178,13 @@ class EVENTS_EXPORT X11EventSource {
   XAtom dummy_atom_;
   std::unique_ptr<XScopedEventSelector> dummy_window_events_;
 
+  // Outstanding requests that should be serviced.
+  std::list<std::unique_ptr<Request>> request_queue_;
+
+  // For HasNextReply();
+  void* next_reply_;
+  xcb_generic_error_t* next_error_;
+
   // Keeps track of whether this source should continue to dispatch all the
   // available events.
   bool continue_stream_ = true;