Revert of ServiceWorker: Prevent worker script with incorrect MIME type to be...

Revert of ServiceWorker: Prevent worker script with incorrect MIME type to be registered. (https://codereview.chromium.org/446323002/)

Reason for revert:
Suspected for breakage on Mac waterfall bots (10.6/10.7)

test ServiceWorkerBrowserTest.ImportsBustMemcache failing since

http://build.chromium.org/p/chromium.mac/builders/Mac10.6%20Tests%20%281%29/builds/54624
http://build.chromium.org/p/chromium.mac/builders/Mac10.7%20Tests%20%281%29/builds/25141

Times out. errors like

[ RUN      ] ServiceWorkerBrowserTest.ImportsBustMemcache
[16435:263:0812/001516:2160051331590:INFO:CONSOLE(13)] "initial unregistration done", source: http://127.0.0.1:58683/service_worker/imports_bust_memcache.html (13)
BrowserTestBase signal handler received SIGTERM. Backtrace:
0   content_browsertests                0x6249bcaa base::debug::StackTrace::StackTrace() + 26
..
11  AppKit                              0x96eeddd6 -[NSApplication nextEventMatchingMask:untilDate:inMode:dequeue:] + 156
12  AppKit                              0x96eb01f3 -[NSApplication run] + 821
..
19  content_browsertests                0x6228bf46 content::TitleWatcher::WaitAndGetTitle() + 118
20  content_browsertests                0x61ed5252 content::ServiceWorkerBrowserTest_ImportsBustMemcache_Test::RunTestOnMainThread() + 530
[649/649] ServiceWorkerBrowserTest.ImportsBustMemcache (TIMED OUT)

Original issue's description:
> ServiceWorker: Prevent worker script with incorrect MIME type to be registered.
> 
> Fix for spec update: https://github.com/slightlyoff/ServiceWorker/issues/380.
> A valid worker script MIME type should be one of below:
> application/x-javascript
> text/javascript
> application/javascript
> 
> BUG=400604
> TEST=https://codereview.chromium.org/448063002/
> 
> Committed: https://src.chromium.org/viewvc/chrome?view=rev&revision=288922

TBR=falken@chromium.org,michaeln@chromium.org,thestig@chromium.org,xiang.long@intel.com
NOTREECHECKS=true
NOTRY=true
BUG=400604

Review URL: https://codereview.chromium.org/459383002

Cr-Commit-Position: refs/heads/master@{#288927}
git-svn-id: svn://svn.chromium.org/chrome/trunk/src@288927 0039d316-1c4b-4281-b951-d872f2087c98

chrome/browser/chrome_service_worker_browsertest.cc

@@ -49,8 +49,6 @@ static void ExpectResultAndRun(bool expected,
 IN_PROC_BROWSER_TEST_F(ChromeServiceWorkerTest,
                        CanShutDownWithRegisteredServiceWorker) {
   WriteFile(FILE_PATH_LITERAL("service_worker.js"), "");
-  WriteFile(FILE_PATH_LITERAL("service_worker.js.mock-http-headers"),
-            "HTTP/1.1 200 OK\nContent-Type: text/javascript");
 
   embedded_test_server()->ServeFilesFromDirectory(service_worker_dir_.path());
   ASSERT_TRUE(embedded_test_server()->InitializeAndWaitUntilReady());

content/browser/service_worker/service_worker_write_to_cache_job.cc

@@ -301,18 +301,6 @@ void ServiceWorkerWriteToCacheJob::OnResponseStarted(
     // response to our consumer, just don't cache it?
     return;
   }
-  // To prevent most user-uploaded content from being used as a serviceworker.
-  if (version_->script_url() == url_) {
-    std::string mime_type;
-    request->GetMimeType(&mime_type);
-    if (mime_type != "application/x-javascript" &&
-        mime_type != "text/javascript" &&
-        mime_type != "application/javascript") {
-      AsyncNotifyDoneHelper(net::URLRequestStatus(
-          net::URLRequestStatus::FAILED, net::ERR_FAILED));
-      return;
-    }
-  }
   WriteHeadersToCache();
 }
 

content/test/data/service_worker/fetch_event.js.mock-http-headers

-HTTP/1.1 200 OK
-Content-Type: text/javascript

content/test/data/service_worker/fetch_event_reload.js.mock-http-headers

-HTTP/1.1 200 OK
-Content-Type: text/javascript

content/test/data/service_worker/sync.js.mock-http-headers

-HTTP/1.1 200 OK
-Content-Type: text/javascript

content/test/data/service_worker/worker.js.mock-http-headers

-HTTP/1.1 200 OK
-Content-Type: text/javascript

content/test/data/service_worker/worker_activate_rejected.js.mock-http-headers

-HTTP/1.1 200 OK
-Content-Type: text/javascript

content/test/data/service_worker/worker_install_fulfilled.js.mock-http-headers

-HTTP/1.1 200 OK
-Content-Type: text/javascript

content/test/data/service_worker/worker_install_rejected.js.mock-http-headers

-HTTP/1.1 200 OK
-Content-Type: text/javascript