Split GrDrawBatch and GrVertexBatch into their own files

src/gpu/batches/GrDrawBatch.cpp

+/*
+ * Copyright 2015 Google Inc.
+ *
+ * Use of this source code is governed by a BSD-style license that can be
+ * found in the LICENSE file.
+ */
+
+#include "GrDrawBatch.h"
+
+GrDrawBatch::GrDrawBatch() : fPipelineInstalled(false) { }
+
+GrDrawBatch::~GrDrawBatch() {
+    if (fPipelineInstalled) {
+        this->pipeline()->~GrPipeline();
+    }
+}
+
+bool GrDrawBatch::installPipeline(const GrPipeline::CreateArgs& args) {
+    GrPipelineOptimizations opts;
+    void* location = fPipelineStorage.get();
+    if (!GrPipeline::CreateAt(location, args, &opts)) {
+        return false;
+    }
+    this->initBatchTracker(opts);
+    fPipelineInstalled = true;
+    return true;
+}