Rename ol.structs.Buffer to ol.webgl.Buffer

The Buffer class is WebGL specific, and it's not really a "data structure", in the pure sense of the term.

src/ol/webgl/buffer.js

@@ -0,0 +1,56 @@
+goog.provide('ol.webgl.Buffer');
+
+goog.require('goog.array');
+goog.require('goog.webgl');
+goog.require('ol');
+
+
+/**
+ * @enum {number}
+ */
+ol.webgl.BufferUsage = {
+  STATIC_DRAW: goog.webgl.STATIC_DRAW,
+  STREAM_DRAW: goog.webgl.STREAM_DRAW,
+  DYNAMIC_DRAW: goog.webgl.DYNAMIC_DRAW
+};
+
+
+
+/**
+ * @constructor
+ * @param {Array.<number>=} opt_arr Array.
+ * @param {number=} opt_usage Usage.
+ * @struct
+ */
+ol.webgl.Buffer = function(opt_arr, opt_usage) {
+
+  /**
+   * @private
+   * @type {Array.<number>}
+   */
+  this.arr_ = goog.isDef(opt_arr) ? opt_arr : [];
+
+  /**
+   * @private
+   * @type {number}
+   */
+  this.usage_ = goog.isDef(opt_usage) ?
+      opt_usage : ol.webgl.BufferUsage.STATIC_DRAW;
+
+};
+
+
+/**
+ * @return {Array.<number>} Array.
+ */
+ol.webgl.Buffer.prototype.getArray = function() {
+  return this.arr_;
+};
+
+
+/**
+ * @return {number} Usage.
+ */
+ol.webgl.Buffer.prototype.getUsage = function() {
+  return this.usage_;
+};