Track text selection on the browser side (Mac)

content/browser/renderer_host/text_input_manager.cc

Index: content/browser/renderer_host/text_input_manager.cc
diff --git a/content/browser/renderer_host/text_input_manager.cc b/content/browser/renderer_host/text_input_manager.cc
index aa2522f91ca74f1272bd1cbd63eff233b51f6607..7c46df06f69587fbac6b444a401b51cde1e11bb5 100644
--- a/content/browser/renderer_host/text_input_manager.cc
+++ b/content/browser/renderer_host/text_input_manager.cc
@@ -316,4 +316,28 @@ TextInputManager::TextSelection::TextSelection(const TextSelection& other) =
 
 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