Add GN args for GL/GLES interface

Bug: skia:
Change-Id: I8445a6f3641aa43e7b18832c7c228b66dd321f2d
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/201616
Reviewed-by: Brian Salomon <bsalomon@google.com>
Commit-Queue: Kevin Lubick <kjlubick@google.com>
diff --git a/BUILD.gn b/BUILD.gn
index f37d44a..37fd58e 100644
--- a/BUILD.gn
+++ b/BUILD.gn
@@ -71,6 +71,14 @@
   skia_enable_fontmgr_win = is_win
   skia_enable_fontmgr_win_gdi = is_win
 
+  if (is_mac) {
+    skia_gl_standard = "gl"
+  } else if (is_ios) {
+    skia_gl_standard = "gles"
+  } else {
+    skia_gl_standard = ""
+  }
+
   if (is_android) {
     skia_use_vulkan = defined(ndk_api) && ndk_api >= 24
   } else if (is_fuchsia) {
@@ -133,6 +141,11 @@
   if (is_fuchsia) {
     defines += fuchsia_defines
   }
+  if (skia_gl_standard == "gles") {
+    defines += [ "SK_ASSUME_GL_ES=1" ]
+  } else if (skia_gl_standard == "gl") {
+    defines += [ "SK_ASSUME_GL=1" ]
+  }
 }
 
 # Skia internal APIs, used by Skia itself and a few test tools.
@@ -1584,10 +1597,10 @@
       "tools/timer/Timer.cpp",
       "tools/trace/ChromeTracingTracer.cpp",
       "tools/trace/ChromeTracingTracer.h",
-      "tools/trace/SkDebugfTracer.cpp",
-      "tools/trace/SkDebugfTracer.h",
       "tools/trace/EventTracingPriv.cpp",
       "tools/trace/EventTracingPriv.h",
+      "tools/trace/SkDebugfTracer.cpp",
+      "tools/trace/SkDebugfTracer.h",
     ]
     libs = []
     if (is_ios) {