Only call gles2::Terminate when all Display objects are deleted

gpu/command_buffer/tests/egl_test.cc

Index: gpu/command_buffer/tests/egl_test.cc
diff --git a/gpu/command_buffer/tests/egl_test.cc b/gpu/command_buffer/tests/egl_test.cc
index bf7e30e5f81610aafbdf6fa9072756a2f277ea3a..4223308563698ff6867a024d84f70f5cc614a9a7 100644
--- a/gpu/command_buffer/tests/egl_test.cc
+++ b/gpu/command_buffer/tests/egl_test.cc
@@ -6,6 +6,7 @@
 #include "testing/gtest/include/gtest/gtest.h"
 
 #include <EGL/egl.h>
+#include <GLES2/gl2.h>
 
 // This file tests EGL basic interface for command_buffer_gles2, the mode of
 // command buffer where the code is compiled as a standalone dynamic library and
@@ -33,4 +34,108 @@ TEST_F(Test, BasicEGLInitialization) {
   ASSERT_TRUE(success);
 }
 
-}  // namespace gpu
+class TestContext {
+ public:
+  TestContext() {
+    display_ = eglGetDisplay(EGL_DEFAULT_DISPLAY);
+
+    eglInitialize(display_, nullptr, nullptr);
+
+    static const EGLint configAttribs[] = {
+      EGL_SURFACE_TYPE, EGL_PBUFFER_BIT,
+      EGL_RENDERABLE_TYPE, EGL_OPENGL_ES2_BIT,
+      EGL_RED_SIZE, 8,
+      EGL_GREEN_SIZE, 8,
+      EGL_BLUE_SIZE, 8,
+      EGL_ALPHA_SIZE, 8,
+      EGL_NONE
+    };
+    EGLint numConfigs;
+    EGLConfig config;
+    eglChooseConfig(display_, configAttribs, &config, 1, &numConfigs);
+
+    static const EGLint surfaceAttribs[] = {
+      EGL_WIDTH, 1,
+      EGL_HEIGHT, 1,
+      EGL_NONE
+    };
+    surface_ = eglCreatePbufferSurface(display_, config, surfaceAttribs);
+
+    static const EGLint contextAttribs[] = {
+      EGL_CONTEXT_CLIENT_VERSION, 2,
+      EGL_NONE
+    };
+    context_ = eglCreateContext(display_, config, nullptr, contextAttribs);
+  }
+
+  ~TestContext() {
+    eglMakeCurrent(display_, EGL_NO_SURFACE, EGL_NO_SURFACE, EGL_NO_CONTEXT);
+    eglDestroyContext(display_, context_);
+    eglDestroySurface(display_, surface_);
+    eglTerminate(display_);
+  }
+
+  bool IsValid() const {
+    return display_ != EGL_NO_DISPLAY &&
+      context_ != EGL_NO_CONTEXT &&
+      surface_ != EGL_NO_SURFACE;
+  }
+
+  void TestCallGL() {
+    eglMakeCurrent(display_, surface_, surface_, context_);
+
+    typedef GL_APICALL void GL_APIENTRY (*glEnableProc)(GLenum);
+
+    auto address = eglGetProcAddress("glEnable");
+    auto* glEnable = reinterpret_cast<glEnableProc>(address);
+    glEnable(GL_BLEND);
+  }
+
+ private:
+  TestContext(const TestContext&) = delete;
+  TestContext& operator=(const TestContext&) = delete;
+
+ private:
+  EGLDisplay display_;
+  EGLContext context_;
+  EGLSurface surface_;
+};
+
+// Test case for a workaround for an issue in gles2_conform_support.
+//
+// The problem is that every call to eglGetDisplay(EGL_DEFAULT_DISPLAY)
+// returns a new display object and the construction of each display
+// calls to establish a thread local store variable in where to store the
+// current command buffer context.
+// Likewise the destructor of display calls to free the same tls variable.
+//
+// When skia (nanobench) uses multiple instances of command buffer
+// based contexts and one display is destroyed the TLS variable
+// is also destroyed and subsequent command buffer GL calls using another
+// context instance end up accessing free'ed TLS variable.
+//
+// Note that technically there's also a problem in SkCommandBufferContext
+// since it calls eglTerminate for each display, but this is because
+// the current command buffer egl implementation requires this.
+// Overall this functionality is not aligned with the EGL spefication.
+//
+// This testcase tests that we can create multiple command buffer contexts
+// and dispose them without affecting the other.
+TEST(Test, MultipleDisplays) {
+  TestContext first;
+  ASSERT_TRUE(first.IsValid());
+
+  first.TestCallGL();
+
+  {
+    TestContext second;
+    ASSERT_TRUE(second.IsValid());
+
+    second.TestCallGL();
+  }
+
+  first.TestCallGL();
+}
+
+} // namespace gpu
+