command_buffer_gles2: Implement EGL default Display as a global object

gpu/gles2_conform_support/egl/thread_state.h

+// Copyright (c) 2016 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#ifndef GPU_GLES2_CONFORM_SUPPORT_EGL_STATE_H_
+#define GPU_GLES2_CONFORM_SUPPORT_EGL_STATE_H_
+
+#include "base/macros.h"
+#include "base/memory/ref_counted.h"
+#include <EGL/egl.h>
+
+namespace egl {
+
+class Context;
+class Display;
+class Surface;
+
+// Thread-local API state of EGL.
+class ThreadState {
+ public:
+  // Factory getter for the class. Should only be called by the API layer, and
+  // then passed through Display in order to avoid lock issues.
+  static ThreadState* Get();
+  static void ReleaseThread();
+
+  Surface* current_surface() const { return current_surface_.get(); }
+  Context* current_context() const { return current_context_.get(); }
+
+  template <typename T>
+  T ReturnError(EGLint error, T return_value) {
+    error_code_ = error;
+    return return_value;
+  }
+  template <typename T>
+  T ReturnSuccess(T return_value) {
+    error_code_ = EGL_SUCCESS;
+    return return_value;
+  }
+  EGLint ConsumeErrorCode();
+
+  Display* GetDefaultDisplay();
+  Display* GetDisplay(EGLDisplay);
+
+  // RAII class for ensuring that ThreadState current context
+  // is reflected in the gfx:: and gles:: global variables.
+  class AutoCurrentContextRestore {
+   public:
+    AutoCurrentContextRestore(ThreadState*);
+    ~AutoCurrentContextRestore();
+    void SetCurrent(Surface*, Context*);
+
+   private:
+    ThreadState* thread_state_;
+    DISALLOW_COPY_AND_ASSIGN(AutoCurrentContextRestore);
+  };
+
+ private:
+  ThreadState();
+  ~ThreadState();
+  void SetCurrent(Surface*, Context*);
+
+  EGLint error_code_;
+  scoped_refptr<Surface> current_surface_;
+  scoped_refptr<Context> current_context_;
+  DISALLOW_COPY_AND_ASSIGN(ThreadState);
+};
+
+}  // namespace egl
+
+#endif