Revert of Optimizes the operation of DeleteDatabase when no backing store...

Revert of Optimizes the operation of DeleteDatabase when no backing store exists. (patchset #5 id:120001 of https://codereview.chromium.org/1071553002/)

Reason for revert:
This appears to have made IndexedDBBrowserTest.DiskFullOnCommit flaky, starting at http://build.chromium.org/p/chromium.memory.fyi/builders/Windows%20Content%20Browser%20%28DrMemory%20full%29%20%286%29/builds/380

[ RUN      ] IndexedDBBrowserTest.DiskFullOnCommit

[1028:1768:0423/085845:4229748:INFO:mock_browsertest_indexed_db_class_factory.cc(258)] FailOperation: class=2, method=2, instanceNum=5, callNum=1
[1028:1768:0423/085845:4229873:INFO:indexed_db_browsertest.cc(77)] Navigating to URL and blocking.
[3872:2724:0423/085859:4243383:ERROR:renderer_main.cc(200)] Running without renderer sandbox

[1028:1096:0423/085958:4302491:ERROR:indexed_db_backing_store.cc(4197)] IndexedDB Write Error: TRANSACTION_COMMIT_METHOD
[1028:1768:0423/090005:4309621:INFO:indexed_db_browsertest.cc(79)] Navigation done.
c:\b\build\slave\drm-cr\build\src\content\browser\indexed_db\indexed_db_browsertest.cc(88): error: Failed
Failed: Starting...<span>FAILED: unexpectedErrorCallback<br></span>
[  FAILED  ] IndexedDBBrowserTest.DiskFullOnCommit, where TypeParam =  and GetParam() =  (130664 ms)

Original issue's description:
> Optimizes the operation of DeleteDatabase when no backing store exists.
>
> When deleting the non existing database in a origin with no existing
> backing store, then in DeleteDatabse(), early exiting before OpenBackingStore,
> so that it wont results in multiple transaction as earlier.
>
> BUG=460236
>
> Committed: https://crrev.com/a4c618a142515773709688bfe3c5753e589afd43
> Cr-Commit-Position: refs/heads/master@{#326473}

TBR=cmumford@chromium.org,jsbell@chromium.org,payal.pandey@samsung.com
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
BUG=460236

Review URL: https://codereview.chromium.org/1106703003

Cr-Commit-Position: refs/heads/master@{#326686}

content/browser/indexed_db/indexed_db_browsertest.cc

@@ -492,14 +492,22 @@ IN_PROC_BROWSER_TEST_F(IndexedDBBrowserTest, DiskFullOnCommit) {
   //       => IndexedDBBackingStore::SetUpMetadata
   //   #2: IndexedDBBackingStore::OpenBackingStore
   //       => IndexedDBBackingStore::CleanUpBlobJournal (no-op)
+  // * Then deletes the database:
+  //   #3: IndexedDBFactoryImpl::DeleteDatabase
+  //       => IndexedDBDatabase::Create
+  //       => IndexedDBBackingStore::CreateIDBDatabaseMetaData
+  //   #4: IndexedDBFactoryImpl::DeleteDatabase
+  //       => IndexedDBDatabase::DeleteDatabase
+  //       => IndexedDBBackingStore::DeleteDatabase
+  //       => IndexedDBBackingStore::CleanUpBlobJournal (no-op)
   // * The test calls open(), to create a new database:
-  //   #3: IndexedDBFactoryImpl::Open
+  //   #5: IndexedDBFactoryImpl::Open
   //       => IndexedDBDatabase::Create
   //       => IndexedDBBackingStore::CreateIDBDatabaseMetaData
-  //   #4: IndexedDBTransaction::Commit - initial "versionchange" transaction
+  //   #6: IndexedDBTransaction::Commit - initial "versionchange" transaction
   // * Once the connection is opened, the test runs:
-  //   #5: IndexedDBTransaction::Commit - the test's "readwrite" transaction)
-  const int instance_num = 5;
+  //   #7: IndexedDBTransaction::Commit - the test's "readwrite" transaction)
+  const int instance_num = 7;
   const int call_num = 1;
   FailOperation(FAIL_CLASS_LEVELDB_TRANSACTION, FAIL_METHOD_COMMIT_DISK_FULL,
                 instance_num, call_num);

content/browser/indexed_db/indexed_db_factory_impl.cc

@@ -257,26 +257,6 @@ void IndexedDBFactoryImpl::DeleteDatabase(
     return;
   }
 
-  std::vector<base::string16> names = backing_store->GetDatabaseNames(&s);
-  if (!s.ok()) {
-    DLOG(ERROR) << "Internal error getting database names";
-    IndexedDBDatabaseError error(blink::WebIDBDatabaseExceptionUnknownError,
-                                 "Internal error opening backing store for "
-                                 "indexedDB.deleteDatabase.");
-    callbacks->OnError(error);
-    backing_store = NULL;
-    if (s.IsCorruption())
-      HandleBackingStoreCorruption(origin_url, error);
-    return;
-  }
-  if (!ContainsValue(names, name)) {
-    const int64 version = 0;
-    callbacks->OnSuccess(version);
-    backing_store = NULL;
-    ReleaseBackingStore(origin_url, false /* immediate */);
-    return;
-  }
-
   scoped_refptr<IndexedDBDatabase> database = IndexedDBDatabase::Create(
       name, backing_store.get(), this, unique_identifier, &s);
   if (!database.get()) {