Allow gpu ResourceHandle class to be shared for multiple purposes

src/gpu/GrResourceHandle.h

+/*

[robertphillips, 2016/05/06 15:09:00]

space these over 1 ?

[egdaniel, 2016/05/06 17:08:00]

Done.

+* Copyright 2016 Google Inc.
+*
+* Use of this source code is governed by a BSD-style license that can be
+* found in the LICENSE file.
+*/
+
+#include "SkTypes.h"
+
+#ifndef GrResourceHandle_DEFINED
+#define GrResourcehandle_DEFINED
+
+// Opaque handle to a resource
+class GrResourceHandle {
+public:
+    GrResourceHandle(int value)
+        : fValue(value) {
+        SkASSERT(this->isValid());
+    }
+

[robertphillips, 2016/05/06 15:09:00]

1 line ?

[egdaniel, 2016/05/06 17:08:00]

Done.

+    GrResourceHandle()
+        : fValue(kInvalid_ResourceHandle) {
+    }
+
+    bool operator==(const GrResourceHandle& other) const { return other.fValue == fValue; }
+    bool isValid() const { return kInvalid_ResourceHandle != fValue; }
+    int toIndex() const { SkASSERT(this->isValid()); return fValue; }
+
+private:
+    static const int kInvalid_ResourceHandle = -1;
+    int fValue;
+};
+
+#endif