TaskManager: when shown or activated, select the last active tab.

chrome/browser/ui/task_manager/task_manager_table_model.cc

Index: chrome/browser/ui/task_manager/task_manager_table_model.cc
diff --git a/chrome/browser/ui/task_manager/task_manager_table_model.cc b/chrome/browser/ui/task_manager/task_manager_table_model.cc
index d921daa251a020ca5ad11d04971afc14ed8afd12..76108a6c87a9428c5e79df3f0f4887d327263834 100644
--- a/chrome/browser/ui/task_manager/task_manager_table_model.cc
+++ b/chrome/browser/ui/task_manager/task_manager_table_model.cc
@@ -797,6 +797,16 @@ void TaskManagerTableModel::ToggleColumnVisibility(int column_id) {
   UpdateRefreshTypes(column_id, new_visibility);
 }
 
+int TaskManagerTableModel::GetRowForWebContents(
+    content::WebContents* web_contents) {
+  TaskId task_id =
+      observed_task_manager()->GetTaskIdForWebContents(web_contents);
+  auto index = std::find(tasks_.begin(), tasks_.end(), task_id);
+  if (index == tasks_.end())
+    return -1;
+  return static_cast<int>(index - tasks_.begin());
+}
+
 void TaskManagerTableModel::StartUpdating() {
   TaskManagerInterface::GetTaskManager()->AddObserver(this);
   tasks_ = observed_task_manager()->GetTaskIdsList();