Change chrome.filesystem to handle the Chrome OS Drive file entries directly.

chrome/browser/extensions/api/file_system/file_system_apitest.cc

Index: chrome/browser/extensions/api/file_system/file_system_apitest.cc
diff --git a/chrome/browser/extensions/api/file_system/file_system_apitest.cc b/chrome/browser/extensions/api/file_system/file_system_apitest.cc
index 9b8371e38a70df695abfe481b292fb15950e13a4..988d8d3daf9a6fb0d829b106bea8aa75c0320da2 100644
--- a/chrome/browser/extensions/api/file_system/file_system_apitest.cc
+++ b/chrome/browser/extensions/api/file_system/file_system_apitest.cc
@@ -16,6 +16,8 @@ class FileSystemApiTest : public extensions::PlatformAppBrowserTest {
     extensions::PlatformAppBrowserTest::SetUpCommandLine(command_line);
     test_root_folder_ = test_data_dir_.AppendASCII("api_test")
         .AppendASCII("file_system");
+    FileSystemChooseEntryFunction::RegisterTempExternalFileSystemForTest(
+        "test_root", test_root_folder_);
   }
 
   virtual void TearDown() OVERRIDE {
@@ -30,6 +32,9 @@ class FileSystemApiTest : public extensions::PlatformAppBrowserTest {
       ADD_FAILURE() << "CreateUniqueTempDir failed";
       return base::FilePath();
     }
+    FileSystemChooseEntryFunction::RegisterTempExternalFileSystemForTest(
+        "test_temp", temp_dir_.path());
+
     base::FilePath destination = temp_dir_.path().AppendASCII(destination_name);
     if (copy_gold) {
       base::FilePath source = test_root_folder_.AppendASCII("gold.txt");