Re-land "Fix glGetIntegerv(GL_TEXTURE_BINDING_EXTERNAL_OES, ...)"

BUG=angleproject:1332

Change-Id: Ie970466c4528cb80b2363d0c0683da2d9c23c4f4
Reviewed-on: https://chromium-review.googlesource.com/392267
Commit-Queue: John Bauman <jbauman@chromium.org>
Reviewed-by: Jamie Madill <jmadill@chromium.org>
diff --git a/src/libANGLE/State.cpp b/src/libANGLE/State.cpp
index 4d73304..f7d4850 100644
--- a/src/libANGLE/State.cpp
+++ b/src/libANGLE/State.cpp
@@ -1744,6 +1744,11 @@
         *params =
             getSamplerTextureId(static_cast<unsigned int>(mActiveSampler), GL_TEXTURE_2D_ARRAY);
         break;
+      case GL_TEXTURE_BINDING_EXTERNAL_OES:
+          ASSERT(mActiveSampler < mMaxCombinedTextureImageUnits);
+          *params = getSamplerTextureId(static_cast<unsigned int>(mActiveSampler),
+                                        GL_TEXTURE_EXTERNAL_OES);
+          break;
       case GL_UNIFORM_BUFFER_BINDING:
         *params = mGenericUniformBuffer.id();
         break;