Rename Transfer[Src|Dst] to Copy[Src|Dst]

This is to match the equivalent rename in WebGPU's IDL.

BUG=dawn:22

Change-Id: Ibdf75869e58835d984df559878b884c55310a403
Reviewed-on: https://dawn-review.googlesource.com/c/dawn/+/8623
Commit-Queue: Corentin Wallez <cwallez@chromium.org>
Reviewed-by: Yunchao He <yunchao.he@intel.com>
diff --git a/src/dawn_native/Buffer.cpp b/src/dawn_native/Buffer.cpp
index dd568f5..4930e28 100644
--- a/src/dawn_native/Buffer.cpp
+++ b/src/dawn_native/Buffer.cpp
@@ -91,15 +91,15 @@
         dawn::BufferUsageBit usage = descriptor->usage;
 
         const dawn::BufferUsageBit kMapWriteAllowedUsages =
-            dawn::BufferUsageBit::MapWrite | dawn::BufferUsageBit::TransferSrc;
+            dawn::BufferUsageBit::MapWrite | dawn::BufferUsageBit::CopySrc;
         if (usage & dawn::BufferUsageBit::MapWrite && (usage & kMapWriteAllowedUsages) != usage) {
-            return DAWN_VALIDATION_ERROR("Only TransferSrc is allowed with MapWrite");
+            return DAWN_VALIDATION_ERROR("Only CopySrc is allowed with MapWrite");
         }
 
         const dawn::BufferUsageBit kMapReadAllowedUsages =
-            dawn::BufferUsageBit::MapRead | dawn::BufferUsageBit::TransferDst;
+            dawn::BufferUsageBit::MapRead | dawn::BufferUsageBit::CopyDst;
         if (usage & dawn::BufferUsageBit::MapRead && (usage & kMapReadAllowedUsages) != usage) {
-            return DAWN_VALIDATION_ERROR("Only TransferDst is allowed with MapRead");
+            return DAWN_VALIDATION_ERROR("Only CopyDst is allowed with MapRead");
         }
 
         return {};
@@ -374,8 +374,8 @@
             return DAWN_VALIDATION_ERROR("Buffer subdata out of range");
         }
 
-        if (!(mUsage & dawn::BufferUsageBit::TransferDst)) {
-            return DAWN_VALIDATION_ERROR("Buffer needs the transfer dst usage bit");
+        if (!(mUsage & dawn::BufferUsageBit::CopyDst)) {
+            return DAWN_VALIDATION_ERROR("Buffer needs the CopyDst usage bit");
         }
 
         return {};