Added an extra sync token field for extra command buffer identification.

content/common/gpu/gpu_command_buffer_stub.cc

Index: content/common/gpu/gpu_command_buffer_stub.cc
diff --git a/content/common/gpu/gpu_command_buffer_stub.cc b/content/common/gpu/gpu_command_buffer_stub.cc
index 39a75d2165055f20ca43cbe75afacd72bb67fcb4..0a9cb8483050689aa914d12557929d7eee559ebf 100644
--- a/content/common/gpu/gpu_command_buffer_stub.cc
+++ b/content/common/gpu/gpu_command_buffer_stub.cc
@@ -937,7 +937,7 @@ void GpuCommandBufferStub::OnRetireSyncPoint(uint32 sync_point) {
     // We can simply use the global sync point number as the release count with
     // 0 for the command buffer ID (under normal circumstances 0 is invalid so
     // will not be used) until the old sync points are replaced.
-    gpu::SyncToken sync_token(gpu::CommandBufferNamespace::GPU_IO, 0,
+    gpu::SyncToken sync_token(gpu::CommandBufferNamespace::GPU_IO, 0, 0,
                               sync_point);
     mailbox_manager->PushTextureUpdates(sync_token);
   }
@@ -993,7 +993,7 @@ void GpuCommandBufferStub::PullTextureUpdates(
   gpu::gles2::MailboxManager* mailbox_manager =
       context_group_->mailbox_manager();
   if (mailbox_manager->UsesSync() && MakeCurrent()) {
-    gpu::SyncToken sync_token(namespace_id, command_buffer_id, release);
+    gpu::SyncToken sync_token(namespace_id, 0, command_buffer_id, release);
     mailbox_manager->PullTextureUpdates(sync_token);
   }
 }
@@ -1051,7 +1051,7 @@ void GpuCommandBufferStub::OnFenceSyncRelease(uint64_t release) {
   gpu::gles2::MailboxManager* mailbox_manager =
       context_group_->mailbox_manager();
   if (mailbox_manager->UsesSync() && MakeCurrent()) {
-    gpu::SyncToken sync_token(gpu::CommandBufferNamespace::GPU_IO,
+    gpu::SyncToken sync_token(gpu::CommandBufferNamespace::GPU_IO, 0,
                               command_buffer_id_, release);
     mailbox_manager->PushTextureUpdates(sync_token);
   }