Fix a mouse lock problem on Windows where in clicks outside the web page would also cause mouse loc…

content/browser/renderer_host/render_widget_host_view_aura.cc

Index: content/browser/renderer_host/render_widget_host_view_aura.cc
diff --git a/content/browser/renderer_host/render_widget_host_view_aura.cc b/content/browser/renderer_host/render_widget_host_view_aura.cc
index 8d3df3bd923206398feeb86662585936116c3336..77289728fc732dddf375ecc521104d06ba872e32 100644
--- a/content/browser/renderer_host/render_widget_host_view_aura.cc
+++ b/content/browser/renderer_host/render_widget_host_view_aura.cc
@@ -1522,11 +1522,13 @@ void RenderWidgetHostViewAura::UnlockMouse() {
 
   mouse_locked_ = false;
 
-#if !defined(OS_WIN)
-  window_->ReleaseCapture();
-#else
+  if (window_->HasCapture())
+    window_->ReleaseCapture();
+
+#if defined(OS_WIN)
   ::ClipCursor(NULL);
 #endif
+
   window_->MoveCursorTo(unlocked_mouse_position_);
   aura::client::CursorClient* cursor_client =
       aura::client::GetCursorClient(root_window);