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/util/shader_utils.cpp b/util/shader_utils.cpp
index 4970f62..60fcd60 100644
--- a/util/shader_utils.cpp
+++ b/util/shader_utils.cpp
@@ -35,7 +35,7 @@
     GLuint shader = glCreateShader(type);
 
     const char *sourceArray[1] = { source.c_str() };
-    glShaderSource(shader, 1, sourceArray, NULL);
+    glShaderSource(shader, 1, sourceArray, nullptr);
     glCompileShader(shader);
 
     GLint compileResult;
@@ -51,7 +51,7 @@
         if (infoLogLength > 1)
         {
             std::vector<GLchar> infoLog(infoLogLength);
-            glGetShaderInfoLog(shader, static_cast<GLsizei>(infoLog.size()), NULL, &infoLog[0]);
+            glGetShaderInfoLog(shader, static_cast<GLsizei>(infoLog.size()), nullptr, &infoLog[0]);
             std::cerr << "shader compilation failed: " << &infoLog[0];
         }
         else