Revert of Reland "Added an extra sync token field for extra command buffer..."

content/common/gpu/client/gpu_channel_host.cc

Index: content/common/gpu/client/gpu_channel_host.cc
diff --git a/content/common/gpu/client/gpu_channel_host.cc b/content/common/gpu/client/gpu_channel_host.cc
index 652f93a797db812e4f26f7f3a2abbddcb1686c81..80dfe0a48a074fe5ecd3040dd6a5c9e2361922f6 100644
--- a/content/common/gpu/client/gpu_channel_host.cc
+++ b/content/common/gpu/client/gpu_channel_host.cc
@@ -162,17 +162,6 @@
   return 0;
 }
 
-void GpuChannelHost::FlushPendingStream(int32 stream_id) {
-  AutoLock lock(context_lock_);
-  auto flush_info_iter = stream_flush_info_.find(stream_id);
-  if (flush_info_iter == stream_flush_info_.end())
-    return;
-
-  StreamFlushInfo& flush_info = flush_info_iter->second;
-  if (flush_info.flush_pending)
-    InternalFlush(&flush_info);
-}
-
 void GpuChannelHost::InternalFlush(StreamFlushInfo* flush_info) {
   context_lock_.AssertAcquired();
   DCHECK(flush_info);
@@ -407,10 +396,7 @@
 }
 
 int32 GpuChannelHost::GenerateStreamID() {
-  const int32 stream_id = next_stream_id_.GetNext();
-  DCHECK_NE(0, stream_id);
-  DCHECK_NE(kDefaultStreamId, stream_id);
-  return stream_id;
+  return next_stream_id_.GetNext();
 }
 
 uint32_t GpuChannelHost::ValidateFlushIDReachedServer(int32 stream_id,