Revert of FileWriter should not use deprecated {,un}setPendingActivity

Source/modules/filesystem/FileWriter.cpp

Index: Source/modules/filesystem/FileWriter.cpp
diff --git a/Source/modules/filesystem/FileWriter.cpp b/Source/modules/filesystem/FileWriter.cpp
index d6ba4024e032b43870b3d31edeffd9769821c06a..aae5e2e70d43c168c5b32e4b192f2bd13ea39935 100644
--- a/Source/modules/filesystem/FileWriter.cpp
+++ b/Source/modules/filesystem/FileWriter.cpp
@@ -87,11 +87,6 @@
     m_readyState = DONE;
 }
 
-bool FileWriter::hasPendingActivity() const
-{
-    return m_operationInProgress != OperationNone || m_queuedOperation != OperationNone || m_readyState != WRITING;
-}
-
 void FileWriter::write(Blob* data, ExceptionState& exceptionState)
 {
     ASSERT(writer());
@@ -209,6 +204,7 @@
     if (complete) {
       if (numAborts == m_numAborts)
           signalCompletion(FileError::OK);
+      unsetPendingActivity(this);
     }
 }
 
@@ -225,6 +221,7 @@
         setPosition(length());
     m_operationInProgress = OperationNone;
     signalCompletion(FileError::OK);
+    unsetPendingActivity(this);
 }
 
 void FileWriter::didFail(blink::WebFileError code)
@@ -240,6 +237,7 @@
     m_blobBeingWritten.clear();
     m_operationInProgress = OperationNone;
     signalCompletion(static_cast<FileError::ErrorCode>(code));
+    unsetPendingActivity(this);
 }
 
 void FileWriter::completeAbort()
@@ -249,6 +247,7 @@
     Operation operation = m_queuedOperation;
     m_queuedOperation = OperationNone;
     doOperation(operation);
+    unsetPendingActivity(this);
 }
 
 void FileWriter::doOperation(Operation operation)
@@ -259,12 +258,14 @@
         ASSERT(m_truncateLength == -1);
         ASSERT(m_blobBeingWritten.get());
         ASSERT(m_readyState == WRITING);
+        setPendingActivity(this);
         writer()->write(position(), m_blobBeingWritten->uuid());
         break;
     case OperationTruncate:
         ASSERT(m_operationInProgress == OperationNone);
         ASSERT(m_truncateLength >= 0);
         ASSERT(m_readyState == WRITING);
+        setPendingActivity(this);
         writer()->truncate(m_truncateLength);
         break;
     case OperationNone: