Fix crash in ResetCursor.

During the GPU Channel set up, we queue Cursor related IPC calls and
calls related to Widget delegate creation is done only after the channel
is established. This has a effect that the cursor related IPC calls are
handled first and then calls related to Widget delegate creation. However
ResetCursor expects WindowDelegate for the widget to be already
present. Now, we force the creation of WidgetDelegate in OnCursorSet.

This was causing a crash during startup.

Review URL: https://codereview.chromium.org/698793002

Cr-Commit-Position: refs/heads/master@{#302622}

ui/ozone/platform/dri/dri_cursor.cc

@@ -34,7 +34,6 @@ void DriCursor::SetCursor(gfx::AcceleratedWidget widget,
     return;
 
   cursor_ = cursor;
-  ShowCursor();
 }
 
 void DriCursor::ShowCursor() {

ui/ozone/platform/dri/dri_cursor.h

@@ -28,6 +28,9 @@ class DriCursor : public CursorDelegateEvdev {
                      DriWindowManager* window_manager);
   virtual ~DriCursor();
 
+  // Set's platform_cursor for widget. SetCursor is not responsible for showing
+  // the cursor. ShowCursor needs  to be explicitly called to make the cursor
+  // visible.
   void SetCursor(gfx::AcceleratedWidget widget, PlatformCursor platform_cursor);
   void ShowCursor();
   void HideCursor();

ui/ozone/platform/dri/dri_window.cc

@@ -87,7 +87,13 @@ void DriWindow::Minimize() {}
 void DriWindow::Restore() {}
 
 void DriWindow::SetCursor(PlatformCursor cursor) {
-  window_manager_->cursor()->SetCursor(widget_, cursor);
+  DriCursor* dri_cursor = window_manager_->cursor();
+  dri_cursor->SetCursor(widget_, cursor);
+  // ShowCursor results in a IPC call to GPU. So, we make sure the channel
+  // is connected. OnChannelEstablished guarantees that ShowCursor is called
+  // eventually.
+  if (sender_->IsConnected() && dri_cursor->GetCursorWindow() == widget_)
+    dri_cursor->ShowCursor();
 }
 
 void DriWindow::MoveCursorTo(const gfx::Point& location) {
@@ -114,6 +120,10 @@ uint32_t DriWindow::DispatchEvent(const PlatformEvent& native_event) {
 void DriWindow::OnChannelEstablished() {
   sender_->Send(new OzoneGpuMsg_CreateWindowDelegate(widget_));
   sender_->Send(new OzoneGpuMsg_WindowBoundsChanged(widget_, bounds_));
+
+  DriCursor* dri_cursor = window_manager_->cursor();
+  if (dri_cursor->GetCursorWindow() == widget_)
+    dri_cursor->ShowCursor();
 }
 
 void DriWindow::OnChannelDestroyed() {