Fix race condition in utility process clients

chrome/browser/extensions/webstore_install_helper.cc

Index: chrome/browser/extensions/webstore_install_helper.cc
diff --git a/chrome/browser/extensions/webstore_install_helper.cc b/chrome/browser/extensions/webstore_install_helper.cc
index e9199ed117cd07e29257857460e9ec811bf1aec8..2148937b2e02104d35f851deffadc11809a8f086 100644
--- a/chrome/browser/extensions/webstore_install_helper.cc
+++ b/chrome/browser/extensions/webstore_install_helper.cc
@@ -35,7 +35,6 @@ WebstoreInstallHelper::WebstoreInstallHelper(
       icon_base64_data_(icon_data),
       icon_url_(icon_url),
       context_getter_(context_getter),
-      utility_host_(NULL),
       icon_decode_complete_(false),
       manifest_parse_complete_(false),
       parse_error_(Delegate::UNKNOWN_ERROR) {}
@@ -67,7 +66,8 @@ void WebstoreInstallHelper::Start() {
 
 void WebstoreInstallHelper::StartWorkOnIOThread() {
   CHECK(BrowserThread::CurrentlyOn(BrowserThread::IO));
-  utility_host_ = new UtilityProcessHost(this, BrowserThread::IO);
+  utility_host_ =
+      (new UtilityProcessHost(this, BrowserThread::IO))->AsWeakPtr();
   utility_host_->set_use_linux_zygote(true);
   utility_host_->StartBatchMode();
 
@@ -172,8 +172,10 @@ void WebstoreInstallHelper::ReportResultsIfComplete() {
     return;
 
   // The utility_host_ will take care of deleting itself after this call.
-  utility_host_->EndBatchMode();
-  utility_host_ = NULL;
+  if (utility_host_) {
+    utility_host_->EndBatchMode();
+    utility_host_.reset();
+  }
 
   BrowserThread::PostTask(
       BrowserThread::UI,