[Command buffer] workaround the framebuffer completeness bug for Intel Mac

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 0fd59c5fd6ba1dfb618709f97b1a8269481fd6d2..44f3c21b552f90acd9436a63a40044fac7b8af19 100644
--- a/gpu/command_buffer/service/framebuffer_manager.cc
+++ b/gpu/command_buffer/service/framebuffer_manager.cc
@@ -611,6 +611,43 @@ bool Framebuffer::HasStencilAttachment() const {
   return attachments_.find(GL_STENCIL_ATTACHMENT) != attachments_.end();
 }
 
+bool Framebuffer::ReadBufferHasNoImage() const {
+  if (read_buffer_ == GL_NONE) {
+    return false;
+  }
+  AttachmentMap::const_iterator it = attachments_.find(read_buffer_);
+  return it == attachments_.end();
+}
+
+bool Framebuffer::DrawBuffersHaveMissingImage(GLsizei* num, GLenum* buf) const {
+  DCHECK(num);
+  DCHECK(buf);
+  bool ret = false;
+  for (GLenum i = 0; i < manager_->max_draw_buffers_; ++i) {
+    if (draw_buffers_[i] == GL_NONE) {
+      buf[i] = GL_NONE;
+      continue;
+    }
+    const Attachment* attachment = GetAttachment(draw_buffers_[i]);
+    if (attachment) {
+      buf[i] = GL_COLOR_ATTACHMENT0 + i;
+      ++(*num);
+    } else {
+      buf[i] = GL_NONE;
+      ret = true;
+    }
+  }
+  return ret;
+}
+
+bool Framebuffer::ColorBuffersHaveImage() const {
+  for (GLenum i = 0; i < manager_->max_color_attachments_; i++) {
+    if (attachments_.find(GL_COLOR_ATTACHMENT0 + i) != attachments_.end())
+      return true;
+  }
+  return false;
+}
+
 GLenum Framebuffer::GetReadBufferInternalFormat() const {
   if (read_buffer_ == GL_NONE)
     return 0;