Make AppShimHostManager a RefCountedThreadSafe.

chrome/browser/browser_process_platform_part_mac.mm

Index: chrome/browser/browser_process_platform_part_mac.mm
diff --git a/chrome/browser/browser_process_platform_part_mac.mm b/chrome/browser/browser_process_platform_part_mac.mm
index c83cd5bc48434f2c37c31fab8cfa63fb9cb38768..fb0a81d36914ad4125a49befa16687f4661e728c 100644
--- a/chrome/browser/browser_process_platform_part_mac.mm
+++ b/chrome/browser/browser_process_platform_part_mac.mm
@@ -15,7 +15,7 @@ BrowserProcessPlatformPart::~BrowserProcessPlatformPart() {
 }
 
 void BrowserProcessPlatformPart::StartTearDown() {
-  app_shim_host_manager_.reset();
+  app_shim_host_manager_ = NULL;
 }
 
 void BrowserProcessPlatformPart::AttemptExit() {
@@ -26,7 +26,7 @@ void BrowserProcessPlatformPart::AttemptExit() {
 }
 
 void BrowserProcessPlatformPart::PreMainMessageLoopRun() {
-  app_shim_host_manager_.reset(new AppShimHostManager);
+  app_shim_host_manager_ = new AppShimHostManager;
   AppListService::InitAll(NULL);
 }