Rename Framebuffer::completeness to checkStatus and add an Impl method.

BUG=angle:841

Change-Id: I04b4ffd086424569a15aa21447dd552e0a898928
Reviewed-on: https://chromium-review.googlesource.com/232394
Reviewed-by: Geoff Lang <geofflang@chromium.org>
Tested-by: Geoff Lang <geofflang@chromium.org>
diff --git a/src/libANGLE/validationES3.cpp b/src/libANGLE/validationES3.cpp
index c9c9760..f2f1ebc 100644
--- a/src/libANGLE/validationES3.cpp
+++ b/src/libANGLE/validationES3.cpp
@@ -875,7 +875,7 @@
 
     gl::Framebuffer *framebuffer = context->getState().getReadFramebuffer();
 
-    if (framebuffer->completeness(context->getData()) != GL_FRAMEBUFFER_COMPLETE)
+    if (framebuffer->checkStatus(context->getData()) != GL_FRAMEBUFFER_COMPLETE)
     {
         context->recordError(Error(GL_INVALID_FRAMEBUFFER_OPERATION));
         return false;
@@ -1289,7 +1289,7 @@
     }
 
     const gl::Framebuffer *fbo = context->getState().getDrawFramebuffer();
-    if (!fbo || fbo->completeness(context->getData()) != GL_FRAMEBUFFER_COMPLETE)
+    if (!fbo || fbo->checkStatus(context->getData()) != GL_FRAMEBUFFER_COMPLETE)
     {
         context->recordError(Error(GL_INVALID_FRAMEBUFFER_OPERATION));
         return false;