Add glClientWaitSync to GPU command buffer.

gpu/command_buffer/common/gles2_cmd_utils.cc

Index: gpu/command_buffer/common/gles2_cmd_utils.cc
diff --git a/gpu/command_buffer/common/gles2_cmd_utils.cc b/gpu/command_buffer/common/gles2_cmd_utils.cc
index 638245b7f6edcbad9ee578c51d3fe201ded392e9..c16a962f6d59ba61df57af19e1a78b3573ea57f8 100644
--- a/gpu/command_buffer/common/gles2_cmd_utils.cc
+++ b/gpu/command_buffer/common/gles2_cmd_utils.cc
@@ -846,6 +846,20 @@ size_t GLES2Util::CalcClearBufferfvDataCount(int buffer) {
   }
 }
 
+// static
+void GLES2Util::MapUint64ToTwoUint32(
+    uint64_t v64, uint32_t* v32_0, uint32_t* v32_1) {
+  DCHECK(v32_0 && v32_1);
+  *v32_0 = static_cast<uint32_t>(v64 & 0xFFFFFFFF);
+  *v32_1 = static_cast<uint32_t>((v64 & 0xFFFFFFFF00000000) >> 32);
+}
+
+// static
+uint64_t GLES2Util::MapTwoUint32ToUint64(uint32_t v32_0, uint32_t v32_1) {
+  uint64_t v64 = v32_1;
+  return (v64 << 32) | v32_0;
+}
+
 namespace {
 
 // WebGraphicsContext3DCommandBufferImpl configuration attributes. Those in