Lo-Fi snackbar should only be shown for the first q=low response of a page

components/data_reduction_proxy/content/browser/content_lofi_ui_service.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 "components/data_reduction_proxy/content/browser/content_lofi_ui_service.h"
+
+#include "base/bind.h"
+#include "base/location.h"
+#include "base/single_thread_task_runner.h"
+#include "content/public/browser/render_frame_host.h"
+#include "content/public/browser/resource_request_info.h"
+#include "content/public/browser/web_contents.h"
+#include "net/url_request/url_request.h"
+
+namespace data_reduction_proxy {
+
+ContentLoFiUIService::ContentLoFiUIService(
+    const scoped_refptr<base::SingleThreadTaskRunner>& ui_task_runner,
+    const NotifyLoFiResponseReceivedCallback&
+        notify_lofi_response_received_callback)
+    : ui_task_runner_(ui_task_runner),
+      notify_lofi_response_received_callback_(
+          notify_lofi_response_received_callback) {
+  DCHECK(!notify_lofi_response_received_callback_.is_null());
+}
+
+ContentLoFiUIService::~ContentLoFiUIService() {}
+
+void ContentLoFiUIService::NotifyLoFiReponseReceived(
+    const net::URLRequest& request) {

[tbansal1, 2016/01/05 21:07:09]

Add DCHECK that this is currently on IO thread?

[megjablon, 2016/01/06 17:20:47]

Done.

+  int render_process_id = -1;
+  int render_frame_id = -1;
+  if (content::ResourceRequestInfo::GetRenderFrameForRequest(
+          &request, &render_process_id, &render_frame_id)) {
+    ui_task_runner_->PostTask(
+        FROM_HERE,
+        base::Bind(&ContentLoFiUIService::NotifyLoFiResponseReceivedOnUI,
+                   base::Unretained(this), render_process_id, render_frame_id));
+  }
+}
+
+void ContentLoFiUIService::NotifyLoFiResponseReceivedOnUI(int render_process_id,
+                                                          int render_frame_id) {
+  DCHECK(ui_task_runner_->BelongsToCurrentThread());
+  content::RenderFrameHost* frame =

[tbansal1, 2016/01/05 21:07:09]

nit: const

[megjablon, 2016/01/06 17:20:47]

FromRenderFrameHost takes as non-const pointer so this can't be const

+      content::RenderFrameHost::FromID(render_process_id, render_frame_id);
+  if (frame) {
+    DCHECK(!notify_lofi_response_received_callback_.is_null());
+    content::WebContents* web_contents =
+        content::WebContents::FromRenderFrameHost(frame);
+    notify_lofi_response_received_callback_.Run(web_contents);
+  }
+}
+
+}  // namespace data_reduction_proxy