Enabling TabManager on testing browser process

chrome/test/base/testing_browser_process.cc

Index: chrome/test/base/testing_browser_process.cc
diff --git a/chrome/test/base/testing_browser_process.cc b/chrome/test/base/testing_browser_process.cc
index bbaf05fe2c3a6d2d0bffcc7867598acf39f627ca..b92d3f4f801de4aec4e61aaa4555eeb62641fd67 100644
--- a/chrome/test/base/testing_browser_process.cc
+++ b/chrome/test/base/testing_browser_process.cc
@@ -11,6 +11,7 @@
 #include "chrome/browser/browser_process.h"
 #include "chrome/browser/browser_process_impl.h"
 #include "chrome/browser/lifetime/application_lifetime.h"
+#include "chrome/browser/memory/tab_manager.h"
 #include "chrome/browser/notifications/notification_platform_bridge.h"
 #include "chrome/browser/notifications/notification_ui_manager.h"
 #include "chrome/browser/printing/print_job_manager.h"
@@ -369,7 +370,13 @@ gcm::GCMDriver* TestingBrowserProcess::gcm_driver() {
 }
 
 memory::TabManager* TestingBrowserProcess::GetTabManager() {
+#if defined(OS_WIN) || defined(OS_MACOSX) || defined(OS_LINUX)
+  if (!tab_manager_.get())
+    tab_manager_.reset(new memory::TabManager());
+  return tab_manager_.get();
+#else
   return nullptr;
+#endif
 }
 
 shell_integration::DefaultWebClientState