Keep browser process alive while there are platform apps with background pages running.

chrome/browser/extensions/extension_apitest.h

Index: chrome/browser/extensions/extension_apitest.h
diff --git a/chrome/browser/extensions/extension_apitest.h b/chrome/browser/extensions/extension_apitest.h
index 143f9fd2f2e10c505f07ac731abf52fa09367c82..2c5343fed84a4fb6139c704dde5fa4b7c64c6fd6 100644
--- a/chrome/browser/extensions/extension_apitest.h
+++ b/chrome/browser/extensions/extension_apitest.h
@@ -148,9 +148,15 @@ class ExtensionApiTest : public ExtensionBrowserTest {
   bool RunPageTest(const std::string& page_url, int flags);
 
   // Similar to RunExtensionTest, except used for running tests in platform app
-  // shell windows.
+  // shell windows. After running the test will close all shell windows and wait
+  // for the background page to be unloaded.
   bool RunPlatformAppTest(const char* extension_name);
 
+  // Similar to RunPlatformAppTest, except after running the test returns
+  // without closing shell windows or waiting for the background page to be
+  // unloaded.
+  bool RunPlatformAppTestReturnImmediately(const char* extension_name);
+
   // Start the test server, and store details of its state.  Those details
   // will be available to javascript tests using chrome.test.getConfig().
   bool StartTestServer();