Refactoring: replace NULL by nullptr for pointers (3rd CL).

This CL mainly handles passing/returning NULL to/from a function.

BUG=angleproject:2001

Change-Id: I34802f792e710e3d7ff697cbe4701dc1bf5ab009
Reviewed-on: https://chromium-review.googlesource.com/485060
Commit-Queue: Jamie Madill <jmadill@chromium.org>
Reviewed-by: Jamie Madill <jmadill@chromium.org>
diff --git a/src/tests/gl_tests/PBOExtensionTest.cpp b/src/tests/gl_tests/PBOExtensionTest.cpp
index f0c0bd3..96aae22 100644
--- a/src/tests/gl_tests/PBOExtensionTest.cpp
+++ b/src/tests/gl_tests/PBOExtensionTest.cpp
@@ -29,7 +29,8 @@
         {
             glGenBuffers(1, &mPBO);
             glBindBuffer(GL_PIXEL_PACK_BUFFER, mPBO);
-            glBufferData(GL_PIXEL_PACK_BUFFER, 4 * getWindowWidth() * getWindowHeight(), NULL, GL_STATIC_DRAW);
+            glBufferData(GL_PIXEL_PACK_BUFFER, 4 * getWindowWidth() * getWindowHeight(), nullptr,
+                         GL_STATIC_DRAW);
             glBindBuffer(GL_PIXEL_PACK_BUFFER, 0);
 
             const char *vertexShaderSrc = SHADER_SOURCE
@@ -61,7 +62,7 @@
 
             glGenBuffers(1, &mPositionVBO);
             glBindBuffer(GL_ARRAY_BUFFER, mPositionVBO);
-            glBufferData(GL_ARRAY_BUFFER, 128, NULL, GL_DYNAMIC_DRAW);
+            glBufferData(GL_ARRAY_BUFFER, 128, nullptr, GL_DYNAMIC_DRAW);
             glBindBuffer(GL_ARRAY_BUFFER, 0);
         }
         ASSERT_GL_NO_ERROR();