Add basic GL functionality to the passthrough command buffer.

gpu/command_buffer/service/gl_utils.cc

Index: gpu/command_buffer/service/gl_utils.cc
diff --git a/gpu/command_buffer/service/gl_utils.cc b/gpu/command_buffer/service/gl_utils.cc
index 8fca5d4b82b6a118ae9dbdf2b930be28f1935f82..331db1262d34a1e64dedc75901badbc71d179a48 100644
--- a/gpu/command_buffer/service/gl_utils.cc
+++ b/gpu/command_buffer/service/gl_utils.cc
@@ -176,5 +176,13 @@ void PopulateNumericCapabilities(Capabilities* caps,
   }
 }
 
+bool CheckUniqueAndNonNullIds(GLsizei n, const GLuint* client_ids) {
+  if (n <= 0)
+    return true;
+  std::unordered_set<uint32_t> unique_ids(client_ids, client_ids + n);
+  return (unique_ids.size() == static_cast<size_t>(n)) &&
+         (unique_ids.find(0) == unique_ids.end());
+}
+
 }  // namespace gles2
 }  // namespace gpu