Revert "Add method to sk_gpu_test::TestContext to automatically restore the previous context."

This reverts commit 5627d65146cb92624b682389e017d488872228c7.

Reason for revert: Google3

Original change's description:
> Add method to sk_gpu_test::TestContext to automatically restore the previous context.
> 
> The motivation for this is to allow a GM to create a GL context, do some some work in it, and then return to the context that was set when it was invoked.
> 
> Change-Id: Ie8496072a10f8f3ff36a08889e593a6ca961b61a
> Reviewed-on: https://skia-review.googlesource.com/70720
> Commit-Queue: Brian Salomon <bsalomon@google.com>
> Reviewed-by: Brian Osman <brianosman@google.com>

TBR=bsalomon@google.com,brianosman@google.com

Change-Id: Ifb79638c9d4500ca3be9a5be39a5ad78b20247c1
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Reviewed-on: https://skia-review.googlesource.com/72981
Reviewed-by: Brian Osman <brianosman@google.com>
Commit-Queue: Brian Osman <brianosman@google.com>

1 files changed, 50 insertions, 0 deletions

diff --git a/src/pdf/SkScopeExit.h b/src/pdf/SkScopeExit.h
new file mode 100644
index 0000000000..5b7bcdc076
--- /dev/null
+++ b/src/pdf/SkScopeExit.h
@@ -0,0 +1,50 @@
+/*
+ * Copyright 2016 Google Inc.
+ *
+ * Use of this source code is governed by a BSD-style license that can be
+ * found in the LICENSE file.
+ */
+
+#ifndef SkScopeExit_DEFINED
+#define SkScopeExit_DEFINED
+
+#include "SkTypes.h"
+
+/**
+ * SK_AT_SCOPE_EXIT(stmt) evaluates stmt when the current scope ends.
+ *
+ * E.g.
+ *    {
+ *        int x = 5;
+ *        {
+ *           SK_AT_SCOPE_EXIT(x--);
+ *           SkASSERT(x == 5);
+ *        }
+ *        SkASSERT(x == 4);
+ *    }
+ */
+template <typename Fn>
+class SkScopeExit {
+public:
+    SkScopeExit(Fn f) : fFn(std::move(f)) {}
+    ~SkScopeExit() { fFn(); }
+
+private:
+    Fn fFn;
+
+    SkScopeExit(           const SkScopeExit& ) = delete;
+    SkScopeExit& operator=(const SkScopeExit& ) = delete;
+    SkScopeExit(                 SkScopeExit&&) = delete;
+    SkScopeExit& operator=(      SkScopeExit&&) = delete;
+};
+
+template <typename Fn>
+inline SkScopeExit<Fn> SkMakeScopeExit(Fn&& fn) {
+    return {std::move(fn)};
+}
+
+#define SK_AT_SCOPE_EXIT(stmt)                              \
+    SK_UNUSED auto&& SK_MACRO_APPEND_LINE(at_scope_exit_) = \
+        SkMakeScopeExit([&]() { stmt; });
+
+#endif  // SkScopeExit_DEFINED