Revert "Reenable Vulkan validation"

This reverts commit c8ac2e2a.

Reason for revert: It seems like others are running into a problem caused by this. I'll investigate why I didn't see those same issues locally.

Original change's description:
> Reenable Vulkan validation
> 
> The Vulkan validation layer used to error when a platform-specific
> surface (in this case, a X11 surface) was used.
> 
> A build flag which enables the validation layer to recognize that
> platform-specific surface was missing.
> 
> When the Vulkan validation layers moved to ANGLE they also added this
> build flag. As a result, we can re-enable the validation layers on X11.
> 
> BUG=843346
> 
> Change-Id: Ifb634a60a1cd9698b5cf51e03b426a58b4387a5d
> Reviewed-on: https://chromium-review.googlesource.com/c/1300335
> Reviewed-by: Eric Karl <ericrk@chromium.org>
> Commit-Queue: Chris Blume <cblume@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#602961}

TBR=cblume@chromium.org,ericrk@chromium.org

# Not skipping CQ checks because original CL landed > 1 day ago.

Bug: 843346
Change-Id: I28d17d41426102380c7cb246514c08ba462ae248
Reviewed-on: https://chromium-review.googlesource.com/c/1308770Reviewed-by: Chris Blume <cblume@chromium.org>
Reviewed-by: Eric Karl <ericrk@chromium.org>
Commit-Queue: Chris Blume <cblume@chromium.org>
Cr-Commit-Position: refs/heads/master@{#604044}

gpu/vulkan/BUILD.gn

@@ -48,10 +48,6 @@ if (enable_vulkan) {
       "//ui/gfx",
     ]
 
-    if (use_x11) {
-      deps += [ "//third_party/angle/third_party/vulkan-validation-layers:vulkan_validation_layers" ]
-    }
-
     data_deps = []
     if (is_fuchsia) {
       data_deps += [ "//third_party/fuchsia-sdk:vulkan_layers" ]

gpu/vulkan/vulkan_instance.cc

@@ -113,7 +113,9 @@ bool VulkanInstance::Initialize(
   }
 
   std::unordered_set<std::string> desired_layers({
-#if defined(USE_X11) && !defined(USE_OZONE)
+#if !defined(USE_X11) && !defined(USE_OZONE)
+    // TODO(crbug.com/843346): Make validation work in combination with
+    // VK_KHR_xlib_surface or switch to VK_KHR_xcb_surface.
     "VK_LAYER_LUNARG_standard_validation",
 #endif
   });