Mozart: Avoid blocking in glCheckFramebufferStatus().

mojo/ui/gl_renderer.cc

 // Copyright 2015 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "mojo/ui/gl_renderer.h"
 
 #ifndef GL_GLEXT_PROTOTYPES
 #define GL_GLEXT_PROTOTYPES
 #endif
 #include <GLES2/gl2.h>
@@ skipping 85 matching lines @@
   GLuint depth_buffer = 0u;
   if (with_depth) {
     glGenRenderbuffers(1, &depth_buffer);
     glBindRenderbuffer(GL_RENDERBUFFER, depth_buffer);
     glRenderbufferStorage(GL_RENDERBUFFER, GL_DEPTH_COMPONENT16, size.width,
                           size.height);
     glFramebufferRenderbuffer(GL_FRAMEBUFFER, GL_DEPTH_ATTACHMENT,
                               GL_RENDERBUFFER, depth_buffer);
   }
 
-  DCHECK_EQ(static_cast<GLenum>(GL_FRAMEBUFFER_COMPLETE),
-            glCheckFramebufferStatus(GL_FRAMEBUFFER));
+#if DCHECK_IS_ON()
+  // This check causes a flush of the GL pipeline which is too expensive
+  // even in debug mode so only check it the first time as a sanity check.
+  if (!checked_framebuffer_status_) {
+    DCHECK_EQ(static_cast<GLenum>(GL_FRAMEBUFFER_COMPLETE),
+              glCheckFramebufferStatus(GL_FRAMEBUFFER));
+    checked_framebuffer_status_ = true;
+  }
+#endif
 
   glViewport(0, 0, size.width, size.height);
   callback.Run(gl_scope, size);
 
   if (with_depth)
     glDeleteRenderbuffers(1, &depth_buffer);
   glDeleteFramebuffers(1, &fbo);
 
   return BindTextureResource(gl_scope, std::move(texture));
 }
@@ skipping 45 matching lines @@
 
 void GLRenderer::GLTextureReleaser::Release(bool recyclable) {
   if (provider_) {
     provider_->ReleaseTexture(std::move(texture_info_), recyclable);
     provider_.reset();
   }
 }
 
 }  // namespace ui
 }  // namespace mojo