Creating Threaded Skia GL RE

The RE creates a thread and intializes SkiaGLRenderEngine on it.
This first pass is synchronous communication.

Test: adb shell setprop debug.renderengine.backend "skiaglthreaded"
Change-Id: I9811c51f8cc2a999fb2587067bd5dd3a5a972cd1
diff --git a/libs/renderengine/RenderEngine.cpp b/libs/renderengine/RenderEngine.cpp
index 3e65d9a..45db31c 100644
--- a/libs/renderengine/RenderEngine.cpp
+++ b/libs/renderengine/RenderEngine.cpp
@@ -41,6 +41,9 @@
     if (strcmp(prop, "skiagl") == 0) {
         renderEngineType = RenderEngineType::SKIA_GL;
     }
+    if (strcmp(prop, "skiaglthreaded") == 0) {
+        renderEngineType = RenderEngineType::SKIA_GL_THREADED;
+    }
 
     switch (renderEngineType) {
         case RenderEngineType::THREADED:
@@ -49,6 +52,10 @@
                     [args]() { return android::renderengine::gl::GLESRenderEngine::create(args); });
         case RenderEngineType::SKIA_GL:
             return renderengine::skia::SkiaGLRenderEngine::create(args);
+        case RenderEngineType::SKIA_GL_THREADED:
+            return renderengine::threaded::RenderEngineThreaded::create([args]() {
+                return android::renderengine::skia::SkiaGLRenderEngine::create(args);
+            });
         case RenderEngineType::GLES:
         default:
             ALOGD("RenderEngine with GLES Backend");