Support lazy initialization on the buffers bound into a bind group

BUG=dawn:414

Change-Id: Ice592d6427747941406431709999d08778f0f221
Reviewed-on: https://dawn-review.googlesource.com/c/dawn/+/25861
Reviewed-by: Corentin Wallez <cwallez@chromium.org>
Reviewed-by: Austin Eng <enga@chromium.org>
Commit-Queue: Jiawei Shao <jiawei.shao@intel.com>

src/dawn_native/opengl/CommandBufferGL.cpp

@@ -462,6 +462,10 @@ namespace dawn_native { namespace opengl {
                     texture->EnsureSubresourceContentInitialized(texture->GetAllSubresources());
                 }
             }
+
+            for (BufferBase* bufferBase : usages.buffers) {
+                ToBackend(bufferBase)->EnsureDataInitialized();
+            }
         };
 
         const std::vector<PassResourceUsage>& passResourceUsages = GetResourceUsages().perPass;