Remove legacy GrContext factories function and supporting code/types.

Change-Id: I437a4a0a58bf70ea1b8b0659b099a2af2bfa64fe
Reviewed-on: https://skia-review.googlesource.com/116197
Commit-Queue: Brian Salomon <bsalomon@google.com>
Reviewed-by: Greg Daniel <egdaniel@google.com>
diff --git a/tools/gpu/mock/MockTestContext.cpp b/tools/gpu/mock/MockTestContext.cpp
index 5cc5529..6075bc8 100644
--- a/tools/gpu/mock/MockTestContext.cpp
+++ b/tools/gpu/mock/MockTestContext.cpp
@@ -20,9 +20,7 @@
     ~MockTestContext() override {}
 
     virtual GrBackend backend() override { return kMock_GrBackend; }
-    virtual GrBackendContext backendContext() override {
-        return reinterpret_cast<GrBackendContext>(nullptr);
-    }
+
     void testAbandon() override {}
     void submit() override {}
     void finish() override {}