Update from https://crrev.com/317530

gpu/command_buffer/service/framebuffer_manager.cc

Index: gpu/command_buffer/service/framebuffer_manager.cc
diff --git a/gpu/command_buffer/service/framebuffer_manager.cc b/gpu/command_buffer/service/framebuffer_manager.cc
index d766abb96f04934f5e75464fa58b1d7f85a04aae..3e9e0b2916e2de1656de4451cf7e947daa7531cf 100644
--- a/gpu/command_buffer/service/framebuffer_manager.cc
+++ b/gpu/command_buffer/service/framebuffer_manager.cc
@@ -631,6 +631,14 @@ void FramebufferManager::RemoveFramebuffer(GLuint client_id) {
   }
 }
 
+void Framebuffer::DoUnbindGLAttachmentsForWorkaround(GLenum target) {
+  // Replace all attachments with the default Renderbuffer.
+  for (AttachmentMap::const_iterator it = attachments_.begin();
+       it != attachments_.end(); ++it) {
+    glFramebufferRenderbufferEXT(target, it->first, GL_RENDERBUFFER, 0);
+  }
+}
+
 void Framebuffer::AttachRenderbuffer(
     GLenum attachment, Renderbuffer* renderbuffer) {
   const Attachment* a = GetAttachment(attachment);