DevTools: return remote debugging targets sorted by last active time (as it was long ago).

chrome/browser/android/devtools_manager_delegate_android.cc

Index: chrome/browser/android/devtools_manager_delegate_android.cc
diff --git a/chrome/browser/android/devtools_manager_delegate_android.cc b/chrome/browser/android/devtools_manager_delegate_android.cc
index 10ec47a1133bf1928313f40f67458963da7c1e44..96f58833188456d5dc1055b492e917f0e0fd1ec8 100644
--- a/chrome/browser/android/devtools_manager_delegate_android.cc
+++ b/chrome/browser/android/devtools_manager_delegate_android.cc
@@ -112,6 +112,10 @@ class TabProxyDelegate : public content::DevToolsExternalAgentProxyDelegate,
     return true;
   }
 
+  base::TimeTicks GetLastActivityTime() override {
+    return agent_host_ ? agent_host_->GetLastActivityTime() : base::TimeTicks();
+  }
+
   void SendMessageToBackend(const std::string& message) override {
     if (agent_host_)
       agent_host_->DispatchProtocolMessage(this, message);