fuzzing: Add error injection macros to the Vulkan backend

This will enable fuzzing the Vulkan backend with randomly injected
errors to help ensure the backend properly handles all errors. It also
redefines VkResult in the dawn_native::vulkan namespace such that a
VkResult cannot be used unless it is explicitly wrapped.

Bug: dawn:295
Change-Id: I3ab2f98702a67a61afe06315658a9ab76ed4ccc3
Reviewed-on: https://dawn-review.googlesource.com/c/dawn/+/14520
Commit-Queue: Austin Eng <enga@chromium.org>
Reviewed-by: Kai Ninomiya <kainino@chromium.org>

src/common/BUILD.gn

@@ -67,6 +67,10 @@ config("dawn_internal") {
     defines += [ "DAWN_USE_X11" ]
   }
 
+  if (dawn_enable_error_injection) {
+    defines += [ "DAWN_ENABLE_ERROR_INJECTION" ]
+  }
+
   # Only internal Dawn targets can use this config, this means only targets in
   # this BUILD.gn file.
   visibility = [ ":*" ]

src/common/vulkan_platform.h

@@ -78,18 +78,18 @@ class alignas(kNativeVkHandleAlignment) VkNonDispatchableHandle {
     VkNonDispatchableHandle& operator=(const VkNonDispatchableHandle<Tag, HandleType>&) = default;
 
     // Comparisons between handles
-    bool operator==(VkNonDispatchableHandle<Tag, HandleType> other) {
+    bool operator==(VkNonDispatchableHandle<Tag, HandleType> other) const {
         return mHandle == other.mHandle;
     }
-    bool operator!=(VkNonDispatchableHandle<Tag, HandleType> other) {
+    bool operator!=(VkNonDispatchableHandle<Tag, HandleType> other) const {
         return mHandle != other.mHandle;
     }
 
     // Comparisons between handles and VK_NULL_HANDLE
-    bool operator==(std::nullptr_t) {
+    bool operator==(std::nullptr_t) const {
         return mHandle == 0;
     }
-    bool operator!=(std::nullptr_t) {
+    bool operator!=(std::nullptr_t) const {
         return mHandle != 0;
     }