surfaceflinger: add RenderEngine::mEGLDisplay

It does not make much sense to have EGLConfig/EGLContext but not
EGLDisplay in RenderEngine.  We also need this as we move forward on
making EGL an implementation detail of RenderEngine.

Test: SurfaceFlinger_test
Change-Id: I9e2c9b9817e2c2a9b2555ea575be6dcd91927b79
diff --git a/services/surfaceflinger/RenderEngine/RenderEngine.h b/services/surfaceflinger/RenderEngine/RenderEngine.h
index f8e8aaa..b4839be 100644
--- a/services/surfaceflinger/RenderEngine/RenderEngine.h
+++ b/services/surfaceflinger/RenderEngine/RenderEngine.h
@@ -50,9 +50,10 @@
     };
     static GlesVersion parseGlesVersion(const char* str);
 
+    EGLDisplay mEGLDisplay;
     EGLConfig mEGLConfig;
     EGLContext mEGLContext;
-    void setEGLHandles(EGLConfig config, EGLContext ctxt);
+    void setEGLHandles(EGLDisplay display, EGLConfig config, EGLContext ctxt);
 
     virtual void bindImageAsFramebuffer(EGLImageKHR image, uint32_t* texName, uint32_t* fbName, uint32_t* status) = 0;
     virtual void unbindFramebuffer(uint32_t texName, uint32_t fbName) = 0;
@@ -127,6 +128,7 @@
     virtual size_t getMaxTextureSize() const = 0;
     virtual size_t getMaxViewportDims() const = 0;
 
+    EGLDisplay getEGLDisplay() const;
     EGLConfig getEGLConfig() const;
     EGLContext getEGLContext() const;
 };