Fixes popErrorScope to match the specs.

- Prepares for removal of unnecessary bool return, and just call callbacks appropriately. For now always returns true until all users are updated.
- Removes PushErrorScope from handwritten commands now that we no longer need to do anything special.
- Updates tests to reflect the change and make sure to set EXPECTs before calling functions to make tests easier to follow.

Bug: dawn:1324, dawn:526
Change-Id: I90b09c54f9adbf2d6d50ad20dcedf68b5ed0b1fa
Reviewed-on: https://dawn-review.googlesource.com/c/dawn/+/83942
Reviewed-by: Kai Ninomiya <kainino@chromium.org>
Commit-Queue: Austin Eng <enga@chromium.org>

src/dawn/native/Device.cpp

@@ -543,17 +543,25 @@ namespace dawn::native {
     }
 
     bool DeviceBase::APIPopErrorScope(wgpu::ErrorCallback callback, void* userdata) {
+        // TODO(crbug.com/dawn/1324) Remove return and make function void when users are updated.
+        bool returnValue = true;
+        if (callback == nullptr) {
+            static wgpu::ErrorCallback defaultCallback = [](WGPUErrorType, char const*, void*) {};
+            callback = defaultCallback;
+        }
+        // TODO(crbug.com/dawn/1122): Call callbacks only on wgpuInstanceProcessEvents
+        if (IsLost()) {
+            callback(WGPUErrorType_DeviceLost, "GPU device disconnected", userdata);
+            return returnValue;
+        }
         if (mErrorScopeStack->Empty()) {
-            return false;
+            callback(WGPUErrorType_Unknown, "No error scopes to pop", userdata);
+            return returnValue;
         }
         ErrorScope scope = mErrorScopeStack->Pop();
-        if (callback != nullptr) {
-            // TODO(crbug.com/dawn/1122): Call callbacks only on wgpuInstanceProcessEvents
-            callback(static_cast<WGPUErrorType>(scope.GetErrorType()), scope.GetErrorMessage(),
-                     userdata);
-        }
-
-        return true;
+        callback(static_cast<WGPUErrorType>(scope.GetErrorType()), scope.GetErrorMessage(),
+                 userdata);
+        return returnValue;
     }
 
     PersistentCache* DeviceBase::GetPersistentCache() {