gfx: Use unsigned strides for gpu memory buffers.

gpu/command_buffer/tests/gl_gpu_memory_buffer_unittest.cc

Index: gpu/command_buffer/tests/gl_gpu_memory_buffer_unittest.cc
diff --git a/gpu/command_buffer/tests/gl_gpu_memory_buffer_unittest.cc b/gpu/command_buffer/tests/gl_gpu_memory_buffer_unittest.cc
index 7691e33251c5c47c9e12f8d299aea6c43021fe04..2bc32eca565af8dff82f32343f6b1d6399bd82d0 100644
--- a/gpu/command_buffer/tests/gl_gpu_memory_buffer_unittest.cc
+++ b/gpu/command_buffer/tests/gl_gpu_memory_buffer_unittest.cc
@@ -188,7 +188,7 @@ TEST_P(GpuMemoryBufferTest, Lifecycle) {
   // Map buffer for writing.
   ASSERT_TRUE(buffer->Map());
   ASSERT_NE(nullptr, buffer->memory(0));
-  ASSERT_NE(0, buffer->stride(0));
+  ASSERT_NE(0u, buffer->stride(0));
   uint8_t pixel[] = {255u, 0u, 0u, 255u};
 
   // Assign a value to each pixel.