Add GraphicsEnv to libgui

This singleton class stores information provided by the framework and
makes it available to EGL/GLES/Vulkan loaders. It will eventually
replace vulkan::LoaderData and possibly the egl blob cache directory
storage.

Bug: 33531483
Test: various apps w/ and w/o driver package installed
Change-Id: If8b84fd38428f1cc9fcee8ffc25eb90cd87cedb4
diff --git a/libs/gui/GraphicsEnv.cpp b/libs/gui/GraphicsEnv.cpp
new file mode 100644
index 0000000..99b74bf
--- /dev/null
+++ b/libs/gui/GraphicsEnv.cpp
@@ -0,0 +1,40 @@
+/*
+ * Copyright 2017 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+//#define LOG_NDEBUG 1
+#define LOG_TAG "GraphicsEnv"
+#include <gui/GraphicsEnv.h>
+
+#include <log/log.h>
+
+namespace android {
+
+/*static*/ GraphicsEnv& GraphicsEnv::getInstance() {
+    static GraphicsEnv env;
+    return env;
+}
+
+void GraphicsEnv::setDriverPath(const std::string path) {
+    if (!mDriverPath.empty()) {
+        ALOGV("ignoring attempt to change driver path from '%s' to '%s'",
+                mDriverPath.c_str(), path.c_str());
+        return;
+    }
+    ALOGV("setting driver path to '%s'", path.c_str());
+    mDriverPath = path;
+}
+
+} // namespace android