Use angle::Result in front-end (Part 4)

Handles the gl::Renderbuffer class and its implementation.

Bug: angleproject:2491
Change-Id: I3ef718b492dc39ba640c8f68ed80b536f89ff378
Reviewed-on: https://chromium-review.googlesource.com/c/1283309
Reviewed-by: Jamie Madill <jmadill@chromium.org>
Commit-Queue: Jamie Madill <jmadill@chromium.org>
diff --git a/src/libANGLE/renderer/vulkan/RenderbufferVk.cpp b/src/libANGLE/renderer/vulkan/RenderbufferVk.cpp
index 26059bd..1411da3 100644
--- a/src/libANGLE/renderer/vulkan/RenderbufferVk.cpp
+++ b/src/libANGLE/renderer/vulkan/RenderbufferVk.cpp
@@ -32,21 +32,19 @@
 {
 }
 
-gl::Error RenderbufferVk::onDestroy(const gl::Context *context)
+void RenderbufferVk::onDestroy(const gl::Context *context)
 {
     ContextVk *contextVk = vk::GetImpl(context);
     RendererVk *renderer = contextVk->getRenderer();
 
     mImage.release(renderer);
     renderer->releaseObject(renderer->getCurrentQueueSerial(), &mImageView);
-
-    return gl::NoError();
 }
 
-gl::Error RenderbufferVk::setStorage(const gl::Context *context,
-                                     GLenum internalformat,
-                                     size_t width,
-                                     size_t height)
+angle::Result RenderbufferVk::setStorage(const gl::Context *context,
+                                         GLenum internalformat,
+                                         size_t width,
+                                         size_t height)
 {
     ContextVk *contextVk       = vk::GetImpl(context);
     RendererVk *renderer       = contextVk->getRenderer();
@@ -99,23 +97,24 @@
         }
     }
 
-    return gl::NoError();
+    return angle::Result::Continue();
 }
 
-gl::Error RenderbufferVk::setStorageMultisample(const gl::Context *context,
-                                                size_t samples,
-                                                GLenum internalformat,
-                                                size_t width,
-                                                size_t height)
+angle::Result RenderbufferVk::setStorageMultisample(const gl::Context *context,
+                                                    size_t samples,
+                                                    GLenum internalformat,
+                                                    size_t width,
+                                                    size_t height)
 {
-    UNIMPLEMENTED();
-    return gl::InternalError();
+    ANGLE_VK_UNREACHABLE(vk::GetImpl(context));
+    return angle::Result::Stop();
 }
 
-gl::Error RenderbufferVk::setStorageEGLImageTarget(const gl::Context *context, egl::Image *image)
+angle::Result RenderbufferVk::setStorageEGLImageTarget(const gl::Context *context,
+                                                       egl::Image *image)
 {
-    UNIMPLEMENTED();
-    return gl::InternalError();
+    ANGLE_VK_UNREACHABLE(vk::GetImpl(context));
+    return angle::Result::Stop();
 }
 
 angle::Result RenderbufferVk::getAttachmentRenderTarget(const gl::Context *context,