Quit the message loop by default in ShellConnectionLost when ApplicationRunner is used

This was originally at https://codereview.chromium.org/1814223002/ , but Ben is out and
I need this for tests, so I'm taking over.

BUG=none
TEST=covered by tests
TBR=ben@chromium.org
R=ben@chromium.org

Committed: https://crrev.com/a50f9840749052fbdec087a304548217cc6fd00b
Cr-Commit-Position: refs/heads/master@{#382389}

Review URL: https://codereview.chromium.org/1819063002

Cr-Commit-Position: refs/heads/master@{#382688}

1 files changed, 7 insertions, 2 deletions

diff --git a/mojo/shell/public/cpp/shell_client.h b/mojo/shell/public/cpp/shell_client.h
index d6fca12..aff1aac 100644
--- a/mojo/shell/public/cpp/shell_client.h
+++ b/mojo/shell/public/cpp/shell_client.h
@@ -43,8 +43,13 @@ class ShellClient {
 
   // Called when ShellConnection's ShellClient binding (i.e. the pipe the
   // Mojo Shell has to talk to us over) is closed. A shell client may use this
-  // as a signal to terminate.
-  virtual void ShellConnectionLost();
+  // as a signal to terminate. Return true from this method to tell the
+  // ShellConnection to run its connection lost closure if it has one, false to
+  // prevent it from being run. The default implementation returns true.
+  // When used in conjunction with ApplicationRunner, returning true here quits
+  // the message loop created by ApplicationRunner, which results in the app
+  // quitting.
+  virtual bool ShellConnectionLost();
 
  private:
   DISALLOW_COPY_AND_ASSIGN(ShellClient);