Initial version of external_oes texture support and unit test

src/gpu/gl/egl/GrGLCreateNativeInterface_egl.cpp

Index: src/gpu/gl/egl/GrGLCreateNativeInterface_egl.cpp
diff --git a/src/gpu/gl/egl/GrGLCreateNativeInterface_egl.cpp b/src/gpu/gl/egl/GrGLCreateNativeInterface_egl.cpp
index 703e39d097dd52c16aaaf224cab9ecff38dfc9d5..fef4f0276f3c04d8e8ee9d5c13b024b7ec8f84dd 100644
--- a/src/gpu/gl/egl/GrGLCreateNativeInterface_egl.cpp
+++ b/src/gpu/gl/egl/GrGLCreateNativeInterface_egl.cpp
@@ -14,7 +14,15 @@
 
 static GrGLFuncPtr egl_get_gl_proc(void* ctx, const char name[]) {
     SkASSERT(nullptr == ctx);
-    return eglGetProcAddress(name);
+    GrGLFuncPtr ptr = eglGetProcAddress(name);
+    if (!ptr) {
+        if (0 == strcmp("eglQueryString", name)) {
+            return (GrGLFuncPtr)eglQueryString;
+        } else if (0 == strcmp("eglGetCurrentDisplay", name)) {
+            return (GrGLFuncPtr)eglGetCurrentDisplay;
+        }
+    }
+    return ptr;
 }
 
 const GrGLInterface* GrGLCreateNativeInterface() {