Add render frame observer for CopylessPaste

components/copyless_paste/renderer/copyless_paste_agent.cc

+// Copyright 2017 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/copyless_paste/renderer/copyless_paste_agent.h"
+
+#include "content/public/renderer/render_frame.h"
+#include "third_party/WebKit/public/web/WebDocument.h"
+#include "third_party/WebKit/public/web/WebElement.h"
+#include "third_party/WebKit/public/web/WebLocalFrame.h"
+
+namespace copyless_paste {
+
+using namespace blink;

[dcheng, 2017/04/02 05:50:34]

Nit: forbidden by the Google C++ style guide

+
+CopylessPasteAgent::CopylessPasteAgent(content::RenderFrame* render_frame)
+    : RenderFrameObserver(render_frame) {}
+
+void CopylessPasteAgent::DidMeaningfulLayout(WebMeaningfulLayout layout_type) {
+  if (layout_type != WebMeaningfulLayout::FinishedParsing) {
+    return;
+  }
+  DCHECK(render_frame());
+  if (!render_frame()->IsMainFrame())

[dcheng, 2017/04/02 05:50:34]

Nit: we should just not install a RFO for a non-main frame.

+    return;
+  DCHECK(render_frame()->GetWebFrame());
+  WebDocument doc = render_frame()->GetWebFrame()->document();
+  if (doc.isNull() || doc.body().isNull())

[dcheng, 2017/04/02 05:50:34]

If we're attached, WebDocument should never be null.

+    return;
+  if (!GURL(doc.url()).SchemeIsHTTPOrHTTPS())
+    return;
+
+  doc.extractMetadata();
+}
+
+CopylessPasteAgent::~CopylessPasteAgent() {}
+
+void CopylessPasteAgent::OnDestruct() {
+  delete this;
+}
+
+}  // namespace copyless_paste