[XProto] Use alternate XCB connection for Vulkan

This is needed for [1] which adds the assumption that Chrome makes
all requests on the main Xcb connection.  This CL simply moves the
requests to occur on a separate connection to satisfy this assumption.

[1] https://chromium-review.googlesource.com/c/chromium/src/+/2565440

R=penghuang

Bug: None
Change-Id: Ia85799c460d0fef372121dae3244874130158fa4
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2566342
Auto-Submit: Thomas Anderson <thomasanderson@chromium.org>
Commit-Queue: Peng Huang <penghuang@chromium.org>
Reviewed-by: Peng Huang <penghuang@chromium.org>
Cr-Commit-Position: refs/heads/master@{#832195}

gpu/vulkan/x/vulkan_implementation_x11.cc

@@ -104,7 +104,8 @@ bool VulkanImplementationX11::GetPhysicalDevicePresentationSupport(
     return true;
   auto* connection = x11::Connection::Get();
   return vkGetPhysicalDeviceXcbPresentationSupportKHR(
-      device, queue_family_index, connection->XcbConnection(),
+      device, queue_family_index,
+      connection->GetXlibDisplay().GetXcbConnection(),
       static_cast<xcb_visualid_t>(connection->default_root_visual().visual_id));
 }
 

gpu/vulkan/x/vulkan_surface_x11.cc

@@ -76,7 +76,7 @@ std::unique_ptr<VulkanSurfaceX11> VulkanSurfaceX11::Create(
   VkSurfaceKHR vk_surface;
   const VkXcbSurfaceCreateInfoKHR surface_create_info = {
       .sType = VK_STRUCTURE_TYPE_XCB_SURFACE_CREATE_INFO_KHR,
-      .connection = connection->XcbConnection(),
+      .connection = connection->GetXlibDisplay().GetXcbConnection(),
       .window = static_cast<xcb_window_t>(window),
   };
   VkResult result = vkCreateXcbSurfaceKHR(vk_instance, &surface_create_info,

ui/gfx/x/BUILD.gn

@@ -38,6 +38,15 @@ generate_library_loader("xlib_loader") {
   ]
 }
 
+generate_library_loader("xlib_xcb_loader") {
+  name = "XlibXcbLoader"
+  output_h = "xlib_xcb_loader.h"
+  output_cc = "xlib_xcb_loader.cc"
+  header = "\"ui/gfx/x/xlib_xcb.h\""
+
+  functions = [ "XGetXCBConnection" ]
+}
+
 action("gen_xprotos") {
   visibility = [ ":xprotos" ]
   script = "gen_xproto.py"
@@ -100,6 +109,7 @@ component("xprotos") {
   deps = [
     ":gen_xprotos",
     ":xlib_loader",
+    ":xlib_xcb_loader",
     "//base",
     "//base:i18n",
     "//ui/events/platform",

ui/gfx/x/xlib_support.cc

@@ -9,6 +9,7 @@
 #include "base/logging.h"
 #include "base/no_destructor.h"
 #include "library_loaders/xlib_loader.h"
+#include "library_loaders/xlib_xcb_loader.h"
 
 namespace x11 {
 
@@ -24,6 +25,11 @@ XlibLoader* GetXlibLoader() {
   return xlib_loader.get();
 }
 
+XlibXcbLoader* GetXlibXcbLoader() {
+  static base::NoDestructor<XlibXcbLoader> xlib_xcb_loader;
+  return xlib_xcb_loader.get();
+}
+
 }  // namespace
 
 DISABLE_CFI_ICALL
@@ -34,6 +40,9 @@ void InitXlib() {
 
   CHECK(xlib_loader->Load("libX11.so.6"));
 
+  auto* xlib_xcb_loader = GetXlibXcbLoader();
+  CHECK(xlib_xcb_loader->Load("libX11-xcb.so.1"));
+
   CHECK(xlib_loader->XInitThreads());
 
   // The default Xlib error handler calls exit(1), which we don't want.  This
@@ -103,4 +112,9 @@ XlibDisplayWrapper& XlibDisplayWrapper::operator=(XlibDisplayWrapper&& other) {
   return *this;
 }
 
+DISABLE_CFI_ICALL
+struct xcb_connection_t* XlibDisplayWrapper::GetXcbConnection() {
+  return GetXlibXcbLoader()->XGetXCBConnection(display_);
+}
+
 }  // namespace x11

ui/gfx/x/xlib_support.h

@@ -11,6 +11,7 @@
 #include "base/component_export.h"
 
 struct _XDisplay;
+struct xcb_connection_t;
 
 namespace x11 {
 
@@ -60,6 +61,8 @@ class COMPONENT_EXPORT(X11) XlibDisplayWrapper {
   }
   operator struct _XDisplay *() { return display_; }
 
+  struct xcb_connection_t* GetXcbConnection();
+
   XlibDisplayWrapper(XlibDisplayWrapper&& other);
   XlibDisplayWrapper& operator=(XlibDisplayWrapper&& other);
 

ui/gfx/x/xlib_xcb.h

+// Copyright 2020 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#ifndef UI_GFX_X_XLIB_XCB_H_
+#define UI_GFX_X_XLIB_XCB_H_
+
+extern "C" {
+struct xcb_connection_t* XGetXCBConnection(struct _XDisplay*);
+}
+
+#endif  // UI_GFX_X_XLIB_XCB_H_