Implement CHROMIUM_copy_compressed_texture for D3D11.

BUG=angleproject:1356

Change-Id: Id563997d2921cf558c52a781ae66d8bde58d1f2f
Reviewed-on: https://chromium-review.googlesource.com/339847
Reviewed-by: Geoff Lang <geofflang@chromium.org>
Commit-Queue: Geoff Lang <geofflang@chromium.org>
diff --git a/src/libANGLE/Context.cpp b/src/libANGLE/Context.cpp
index 081ffc2..c4124b3 100644
--- a/src/libANGLE/Context.cpp
+++ b/src/libANGLE/Context.cpp
@@ -3071,6 +3071,15 @@
                                             unpackUnmultiplyAlpha == GL_TRUE, sourceTexture));
 }
 
+void Context::compressedCopyTextureCHROMIUM(GLuint sourceId, GLuint destId)
+{
+    syncStateForTexImage();
+
+    gl::Texture *sourceTexture = getTexture(sourceId);
+    gl::Texture *destTexture   = getTexture(destId);
+    handleError(destTexture->copyCompressedTexture(sourceTexture));
+}
+
 void Context::getBufferPointerv(GLenum target, GLenum /*pname*/, void **params)
 {
     Buffer *buffer = mGLState.getTargetBuffer(target);