Revert of Restore FileSystemProviderApiTest.BigFile. (patchset #1 id:1 of...

Revert of Restore FileSystemProviderApiTest.BigFile. (patchset #1 id:1 of https://codereview.chromium.org/925213002/)

Reason for revert:
FileSystemProviderApiTest.BigFile is still failing, about 98% of runs on cros_trunk bot.

Original issue's description:
> Restore FileSystemProviderApiTest.BigFile.
>
> This test is not more flaky than other tests. There seem to be some test
> launching issue. Sometimes api tests do not start from time to time. It's
> not common though.
>
> Enabling the test, as it's better to have flaky test than no test. The issue
> with launching tests is tracked separately.
>
> TEST=browser_tests: *FileSystemProviderApiTest.BigFile*
> BUG=458122
>
> Committed: https://crrev.com/fae5f10535ecd3215d1e924505301562ed49744a
> Cr-Commit-Position: refs/heads/master@{#316429}

TBR=hirono@chromium.org,mtomasz@chromium.org
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
BUG=458122

Review URL: https://codereview.chromium.org/952623002

Cr-Commit-Position: refs/heads/master@{#317600}

chrome/browser/chromeos/extensions/file_system_provider/file_system_provider_apitest.cc

@@ -56,7 +56,7 @@ IN_PROC_BROWSER_TEST_F(FileSystemProviderApiTest, ReadFile) {
       << message_;
 }
 
-IN_PROC_BROWSER_TEST_F(FileSystemProviderApiTest, BigFile) {
+IN_PROC_BROWSER_TEST_F(FileSystemProviderApiTest, DISABLED_BigFile) {
   ASSERT_TRUE(RunPlatformAppTestWithFlags("file_system_provider/big_file",
                                           kFlagLoadAsComponent))
       << message_;