Improve initialization failure handling in VulkanInstance

In debug builds VulkanInstance::Destroy() was trying to call
vkDestroyDebugReportCallbackEXT and it would DCHECK after a failure to
find that function. That would happen even if Destroy() is called in
after a failed attempt to load Vulkan libs. It doesn't make sense to
DCHECK in that case. Also now vkDestroyDebugReportCallbackEXT() is
called only if debug callbacks were created successfully.

Bug: 861853
Change-Id: I03bbdbb1793ddb74f07352f354d0f70ee739a93a
Reviewed-on: https://chromium-review.googlesource.com/c/1332263
Commit-Queue: Sergey Ulanov <sergeyu@chromium.org>
Reviewed-by: Antoine Labour <piman@chromium.org>
Cr-Commit-Position: refs/heads/master@{#607476}

gpu/vulkan/vulkan_instance.cc

@@ -163,6 +163,7 @@ bool VulkanInstance::Initialize(
     result = vkCreateDebugReportCallbackEXT(vk_instance_, &cb_create_info,
                                             nullptr, &error_callback_);
     if (VK_SUCCESS != result) {
+      error_callback_ = VK_NULL_HANDLE;
       DLOG(ERROR) << "vkCreateDebugReportCallbackEXT(ERROR) failed: " << result;
       return false;
     }
@@ -173,6 +174,7 @@ bool VulkanInstance::Initialize(
     result = vkCreateDebugReportCallbackEXT(vk_instance_, &cb_create_info,
                                             nullptr, &warning_callback_);
     if (VK_SUCCESS != result) {
+      warning_callback_ = VK_NULL_HANDLE;
       DLOG(ERROR) << "vkCreateDebugReportCallbackEXT(WARN) failed: " << result;
       return false;
     }
@@ -219,13 +221,16 @@ bool VulkanInstance::Initialize(
 
 void VulkanInstance::Destroy() {
 #if DCHECK_IS_ON()
-  if (debug_report_enabled_) {
+  if (debug_report_enabled_ && (error_callback_ != VK_NULL_HANDLE ||
+                                warning_callback_ != VK_NULL_HANDLE)) {
     PFN_vkDestroyDebugReportCallbackEXT vkDestroyDebugReportCallbackEXT =
         reinterpret_cast<PFN_vkDestroyDebugReportCallbackEXT>(
             vkGetInstanceProcAddr(vk_instance_,
                                   "vkDestroyDebugReportCallbackEXT"));
     DCHECK(vkDestroyDebugReportCallbackEXT);
+    if (error_callback_ != VK_NULL_HANDLE)
       vkDestroyDebugReportCallbackEXT(vk_instance_, error_callback_, nullptr);
+    if (warning_callback_ != VK_NULL_HANDLE)
       vkDestroyDebugReportCallbackEXT(vk_instance_, warning_callback_, nullptr);
   }
 #endif