Track text selection on the browser side (Mac)

content/browser/renderer_host/text_input_manager.cc

 // Copyright 2016 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/browser/renderer_host/text_input_manager.h"
 
 #include "base/strings/string16.h"
 #include "content/browser/renderer_host/render_widget_host_impl.h"
 #include "content/browser/renderer_host/render_widget_host_view_base.h"
 #include "content/common/view_messages.h"
@@ skipping 298 matching lines @@
 TextInputManager::CompositionRangeInfo::~CompositionRangeInfo() {}
 
 TextInputManager::TextSelection::TextSelection()
     : offset(0), range(gfx::Range::InvalidRange()), text(base::string16()) {}
 
 TextInputManager::TextSelection::TextSelection(const TextSelection& other) =
     default;
 
 TextInputManager::TextSelection::~TextSelection() {}
 
+bool TextInputManager::TextSelection::GetSelectedText(
+    base::string16* selected_text) const {
+  if (text.empty() || range.is_empty())
+    return false;
+
+  size_t pos = range.GetMin() - offset;
+  size_t n = range.length();
+  if (pos + n > text.length()) {
+    LOG(WARNING) << "The text can not fully cover range (selection's end point "
+                    "exceeds text length).";
+    return false;
+  }
+
+  if (pos >= text.length()) {
+    LOG(WARNING) << "The text ca not cover range (selection range's starting "
+                    "point exceeds text length).";
+    return false;
+  }
+
+  selected_text->clear();
+  selected_text->append(text.substr(pos, n));
+  return true;
+}
+
 }  // namespace content