Fix cast warning in UniformsPerf.cpp.

BUG=None

Change-Id: I28af0d2be5ef545e78b8283d43d14078c0d1b62a
Reviewed-on: https://chromium-review.googlesource.com/422491
Reviewed-by: Jamie Madill <jmadill@chromium.org>
diff --git a/src/tests/perf_tests/UniformsPerf.cpp b/src/tests/perf_tests/UniformsPerf.cpp
index e897fb2..ffcbd4e 100644
--- a/src/tests/perf_tests/UniformsPerf.cpp
+++ b/src/tests/perf_tests/UniformsPerf.cpp
@@ -145,8 +145,10 @@
 
     bool isMatrix = params.dataType == DataType::MAT4;
 
-    GLint numVertexUniformVectors   = params.numVertexUniforms * (isMatrix ? 4 : 1);
-    GLint numFragmentUniformVectors = params.numFragmentUniforms * (isMatrix ? 4 : 1);
+    GLint numVertexUniformVectors =
+        static_cast<GLint>(params.numVertexUniforms) * (isMatrix ? 4 : 1);
+    GLint numFragmentUniformVectors =
+        static_cast<GLint>(params.numFragmentUniforms) * (isMatrix ? 4 : 1);
 
     if (numVertexUniformVectors > maxVertexUniformVectors)
     {