Add option --dump-render-tree to content_shell to dump the render tree as text.

content/shell/shell_render_view_observer.cc

 // Copyright (c) 2012 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 "content/shell/shell_render_view_observer.h"
 
+#include "content/public/renderer/render_view.h"
+#include "content/shell/shell_messages.h"
+#include "third_party/WebKit/Source/WebKit/chromium/public/platform/WebCString.h"
+#include "third_party/WebKit/Source/WebKit/chromium/public/platform/WebString.h"
+#include "third_party/WebKit/Source/WebKit/chromium/public/WebDocument.h"
+#include "third_party/WebKit/Source/WebKit/chromium/public/WebElement.h"
+#include "third_party/WebKit/Source/WebKit/chromium/public/WebFrame.h"
+#include "third_party/WebKit/Source/WebKit/chromium/public/WebView.h"
+
+using WebKit::WebFrame;
+using WebKit::WebElement;
+
 namespace content {
 
+namespace {
+
+std::string DumpDocumentText(WebFrame* frame) {
+  // We use the document element's text instead of the body text here because
+  // not all documents have a body, such as XML documents.
+  WebElement documentElement = frame->document().documentElement();
+  if (documentElement.isNull())
+    return std::string();
+  return documentElement.innerText().utf8();
+}
+
+std::string DumpFramesAsText(WebFrame* frame, bool recursive) {
+  std::string result;
+
+  // Add header for all but the main frame. Skip emtpy frames.
+  if (frame->parent() && !frame->document().documentElement().isNull()) {
+    result.append("\n--------\nFrame: '");
+    result.append(frame->name().utf8().data());
+    result.append("'\n--------\n");
+  }
+
+  result.append(DumpDocumentText(frame));
+  result.append("\n");
+
+  if (recursive) {
+    for (WebFrame* child = frame->firstChild(); child;
+         child = child->nextSibling()) {
+      result.append(DumpFramesAsText(child, recursive));
+    }
+  }
+  return result;
+}
+
+}  // namespace
 ShellRenderViewObserver::ShellRenderViewObserver(RenderView* render_view)
     : RenderViewObserver(render_view) {
 }
 
 ShellRenderViewObserver::~ShellRenderViewObserver() {
 }
 
 bool ShellRenderViewObserver::OnMessageReceived(const IPC::Message& message) {
-  return false;
+  bool handled = true;
+  IPC_BEGIN_MESSAGE_MAP(ShellRenderViewObserver, message)
+    IPC_MESSAGE_HANDLER(ShellViewMsg_CaptureTextDump, OnCaptureTextDump)
+    IPC_MESSAGE_UNHANDLED(handled = false)
+  IPC_END_MESSAGE_MAP()
+
+  return handled;
+}
+
+void ShellRenderViewObserver::OnCaptureTextDump(bool recursive) {
+  std::string dump =
+      DumpFramesAsText(render_view()->GetWebView()->mainFrame(), recursive);
+  Send(new ShellViewHostMsg_TextDump(routing_id(), dump));
 }
 
 }  // namespace content