Refactor ResourceHandler API.

content/browser/download/download_resource_handler.cc

Index: content/browser/download/download_resource_handler.cc
diff --git a/content/browser/download/download_resource_handler.cc b/content/browser/download/download_resource_handler.cc
index a0acc44e3ba78627e536e8aec1d0d887d43fdae1..1b7ec843446200547b1317cc825130ccfed0ba5b 100644
--- a/content/browser/download/download_resource_handler.cc
+++ b/content/browser/download/download_resource_handler.cc
@@ -139,25 +139,29 @@ std::unique_ptr<ResourceHandler> DownloadResourceHandler::Create(
   return handler;
 }
 
-bool DownloadResourceHandler::OnRequestRedirected(
+void DownloadResourceHandler::OnRequestRedirected(
     const net::RedirectInfo& redirect_info,
     ResourceResponse* response,
-    bool* defer) {
-  return core_.OnRequestRedirected();
+    bool* defer_or_cancel) {
+  if (!core_.OnRequestRedirected()) {
+    *defer_or_cancel = true;
+    controller()->Cancel();
+  }
 }
 
 // Send the download creation information to the download thread.
-bool DownloadResourceHandler::OnResponseStarted(
-    ResourceResponse* response,
-    bool* defer) {
+void DownloadResourceHandler::OnResponseStarted(ResourceResponse* response,
+                                                bool* defer_or_cancel) {
   // The MIME type in ResourceResponse is the product of
   // MimeTypeResourceHandler.
-  return core_.OnResponseStarted(response->head.mime_type);
+  if (!core_.OnResponseStarted(response->head.mime_type)) {
+    *defer_or_cancel = true;
+    controller()->Cancel();
+  }
 }
 
-bool DownloadResourceHandler::OnWillStart(const GURL& url, bool* defer) {
-  return true;
-}
+void DownloadResourceHandler::OnWillStart(const GURL& url,
+                                          bool* defer_or_cancel) {}
 
 // Create a new buffer, which will be handed to the download thread for file
 // writing and deletion.
@@ -168,8 +172,12 @@ bool DownloadResourceHandler::OnWillRead(scoped_refptr<net::IOBuffer>* buf,
 }
 
 // Pass the buffer to the download file writer.
-bool DownloadResourceHandler::OnReadCompleted(int bytes_read, bool* defer) {
-  return core_.OnReadCompleted(bytes_read, defer);
+void DownloadResourceHandler::OnReadCompleted(int bytes_read,
+                                              bool* defer_or_cancel) {
+  if (!core_.OnReadCompleted(bytes_read, defer_or_cancel)) {
+    *defer_or_cancel = true;
+    controller()->Cancel();
+  }
 }
 
 void DownloadResourceHandler::OnResponseCompleted(