Move MimeTypeResourceHandler before ThrottlingResourceHandler

content/browser/loader/mime_type_resource_handler.cc

Index: content/browser/loader/mime_type_resource_handler.cc
diff --git a/content/browser/loader/mime_type_resource_handler.cc b/content/browser/loader/mime_type_resource_handler.cc
index ab4fca3a8dbdc4780fb66e01878e11c1a5aa31eb..9a48ba75b877963b9e1562ede0acca02e2c73d5f 100644
--- a/content/browser/loader/mime_type_resource_handler.cc
+++ b/content/browser/loader/mime_type_resource_handler.cc
@@ -32,10 +32,8 @@
 #include "net/base/io_buffer.h"
 #include "net/base/mime_sniffer.h"
 #include "net/base/mime_util.h"
-#include "net/base/net_errors.h"
 #include "net/http/http_content_disposition.h"
 #include "net/http/http_response_headers.h"
-#include "net/url_request/url_request.h"
 
 namespace content {
 
@@ -49,20 +47,6 @@ const char kStylesheetAcceptHeader[] = "text/css,*/*;q=0.1";
 const char kImageAcceptHeader[] = "image/webp,image/*,*/*;q=0.8";
 const char kDefaultAcceptHeader[] = "*/*";
 
-// Used to write into an existing IOBuffer at a given offset.
-class DependentIOBuffer : public net::WrappedIOBuffer {
- public:
-  DependentIOBuffer(net::IOBuffer* buf, int offset)
-      : net::WrappedIOBuffer(buf->data() + offset),
-        buf_(buf) {
-  }
-
- private:
-  ~DependentIOBuffer() override {}
-
-  scoped_refptr<net::IOBuffer> buf_;
-};
-
 }  // namespace
 
 MimeTypeResourceHandler::MimeTypeResourceHandler(
@@ -70,14 +54,13 @@ MimeTypeResourceHandler::MimeTypeResourceHandler(
     ResourceDispatcherHostImpl* host,
     PluginService* plugin_service,
     net::URLRequest* request)
-    : LayeredResourceHandler(request, std::move(next_handler)),
-      state_(STATE_STARTING),
+    : BufferedResourceHandler(std::move(next_handler),
+                              request,
+                              net::kMaxBytesToSniff),
       host_(host),
 #if defined(ENABLE_PLUGINS)
       plugin_service_(plugin_service),
 #endif
-      read_buffer_size_(0),
-      bytes_read_(0),
       must_download_(false),
       must_download_is_set_(false),
       weak_ptr_factory_(this) {
@@ -86,48 +69,6 @@ MimeTypeResourceHandler::MimeTypeResourceHandler(
 MimeTypeResourceHandler::~MimeTypeResourceHandler() {
 }
 
-void MimeTypeResourceHandler::SetController(ResourceController* controller) {
-  ResourceHandler::SetController(controller);
-
-  // Downstream handlers see us as their ResourceController, which allows us to
-  // consume part or all of the resource response, and then later replay it to
-  // downstream handler.
-  DCHECK(next_handler_.get());
-  next_handler_->SetController(this);
-}
-
-bool MimeTypeResourceHandler::OnResponseStarted(ResourceResponse* response,
-                                                bool* defer) {
-  response_ = response;
-
-  // A 304 response should not contain a Content-Type header (RFC 7232 section
-  // 4.1). The following code may incorrectly attempt to add a Content-Type to
-  // the response, and so must be skipped for 304 responses.
-  if (!(response_->head.headers.get() &&
-        response_->head.headers->response_code() == 304)) {
-    if (ShouldSniffContent()) {
-      state_ = STATE_BUFFERING;
-      return true;
-    }
-
-    if (response_->head.mime_type.empty()) {
-      // Ugg.  The server told us not to sniff the content but didn't give us
-      // a mime type.  What's a browser to do?  Turns out, we're supposed to
-      // treat the response as "text/plain".  This is the most secure option.
-      response_->head.mime_type.assign("text/plain");
-    }
-
-    // Treat feed types as text/plain.
-    if (response_->head.mime_type == "application/rss+xml" ||
-        response_->head.mime_type == "application/atom+xml") {
-      response_->head.mime_type.assign("text/plain");
-    }
-  }
-
-  state_ = STATE_PROCESSING;
-  return ProcessResponse(defer);
-}
-
 bool MimeTypeResourceHandler::OnWillStart(const GURL& url, bool* defer) {
   const char* accept_value = nullptr;
   switch (GetRequestInfo()->GetResourceType()) {
@@ -168,115 +109,65 @@ bool MimeTypeResourceHandler::OnWillStart(const GURL& url, bool* defer) {
   return next_handler_->OnWillStart(url, defer);
 }
 
-bool MimeTypeResourceHandler::OnWillRead(scoped_refptr<net::IOBuffer>* buf,
-                                         int* buf_size,
-                                         int min_size) {
-  if (state_ == STATE_STREAMING)
-    return next_handler_->OnWillRead(buf, buf_size, min_size);
-
-  DCHECK_EQ(-1, min_size);
-
-  if (read_buffer_.get()) {
-    CHECK_LT(bytes_read_, read_buffer_size_);
-    *buf = new DependentIOBuffer(read_buffer_.get(), bytes_read_);
-    *buf_size = read_buffer_size_ - bytes_read_;
-  } else {
-    if (!next_handler_->OnWillRead(buf, buf_size, min_size))
-      return false;
-
-    read_buffer_ = *buf;
-    read_buffer_size_ = *buf_size;
-    DCHECK_GE(read_buffer_size_, net::kMaxBytesToSniff * 2);
+bool MimeTypeResourceHandler::CanStartReplayInResponseStarted() {
+  // A 304 response should not contain a Content-Type header (RFC 7232 section
+  // 4.1). The following code may incorrectly attempt to add a Content-Type to
+  // the response, and so must be skipped for 304 responses.
+  if (response()->head.headers.get() &&
+      response()->head.headers->response_code() == 304) {
+    return true;
   }
-  return true;
-}
 
-bool MimeTypeResourceHandler::OnReadCompleted(int bytes_read, bool* defer) {
-  if (state_ == STATE_STREAMING)
-    return next_handler_->OnReadCompleted(bytes_read, defer);
+  if (ShouldSniffContent())
+    return false;
 
-  DCHECK_EQ(state_, STATE_BUFFERING);
-  bytes_read_ += bytes_read;
+  if (response()->head.mime_type.empty()) {
+    // Ugg.  The server told us not to sniff the content but didn't give us
+    // a mime type.  What's a browser to do?  Turns out, we're supposed to
+    // treat the response as "text/plain".  This is the most secure option.
+    response()->head.mime_type.assign("text/plain");
+  }
 
-  if (!DetermineMimeType() && (bytes_read > 0))
-    return true;  // Needs more data, so keep buffering.
+  // Treat feed types as text/plain.
+  if (response()->head.mime_type == "application/rss+xml" ||
+      response()->head.mime_type == "application/atom+xml") {
+    response()->head.mime_type.assign("text/plain");
+  }
 
-  state_ = STATE_PROCESSING;
-  return ProcessResponse(defer);
+  return true;
 }
 
-void MimeTypeResourceHandler::OnResponseCompleted(
-    const net::URLRequestStatus& status,
-    const std::string& security_info,
-    bool* defer) {
-  // Upon completion, act like a pass-through handler in case the downstream
-  // handler defers OnResponseCompleted.
-  state_ = STATE_STREAMING;
+bool MimeTypeResourceHandler::CanStartReplayInReadCompleted() {
+  const std::string& type_hint = response()->head.mime_type;
 
-  next_handler_->OnResponseCompleted(status, security_info, defer);
-}
-
-void MimeTypeResourceHandler::Resume() {
-  switch (state_) {
-    case STATE_BUFFERING:
-    case STATE_PROCESSING:
-      NOTREACHED();
-      break;
-    case STATE_REPLAYING:
-      base::ThreadTaskRunnerHandle::Get()->PostTask(
-          FROM_HERE,
-          base::Bind(&MimeTypeResourceHandler::CallReplayReadCompleted,
-                     weak_ptr_factory_.GetWeakPtr()));
-      break;
-    case STATE_STARTING:
-    case STATE_STREAMING:
-      controller()->Resume();
-      break;
-  }
-}
-
-void MimeTypeResourceHandler::Cancel() {
-  controller()->Cancel();
-}
+  std::string new_type;
+  bool made_final_decision =
+      net::SniffMimeType(read_buffer()->data(), bytes_read(), request()->url(),
+                         type_hint, &new_type);
 
-void MimeTypeResourceHandler::CancelAndIgnore() {
-  controller()->CancelAndIgnore();
-}
+  // SniffMimeType() returns false if there is not enough data to determine
+  // the mime type. However, even if it returns false, it returns a new type
+  // that is probably better than the current one.
+  response()->head.mime_type.assign(new_type);
 
-void MimeTypeResourceHandler::CancelWithError(int error_code) {
-  controller()->CancelWithError(error_code);
+  return made_final_decision;
 }
 
-bool MimeTypeResourceHandler::ProcessResponse(bool* defer) {
-  DCHECK_EQ(STATE_PROCESSING, state_);
-
+bool MimeTypeResourceHandler::WillStartReplay(bool* defer) {
   // TODO(darin): Stop special-casing 304 responses.
-  if (!(response_->head.headers.get() &&
-        response_->head.headers->response_code() == 304)) {
-    if (!SelectNextHandler(defer))
-      return false;
-    if (*defer)
-      return true;
-  }
-
-  state_ = STATE_REPLAYING;
-
-  if (!next_handler_->OnResponseStarted(response_.get(), defer))
-    return false;
-
-  if (!read_buffer_.get()) {
-    state_ = STATE_STREAMING;
+  if (response()->head.headers.get() &&
+      response()->head.headers->response_code() == 304) {
     return true;
   }
 
-  if (!*defer)
-    return ReplayReadCompleted(defer);
+  if (!SelectNextHandler(defer))
+    return false;
 
   return true;
 }
 
 bool MimeTypeResourceHandler::ShouldSniffContent() {
-  const std::string& mime_type = response_->head.mime_type;
+  const std::string& mime_type = response()->head.mime_type;
 
   std::string content_type_options;
   request()->GetResponseHeaderByName("x-content-type-options",
@@ -298,24 +189,6 @@ bool MimeTypeResourceHandler::ShouldSniffContent() {
   return false;
 }
 
-bool MimeTypeResourceHandler::DetermineMimeType() {
-  DCHECK_EQ(STATE_BUFFERING, state_);
-
-  const std::string& type_hint = response_->head.mime_type;
-
-  std::string new_type;
-  bool made_final_decision =
-      net::SniffMimeType(read_buffer_->data(), bytes_read_, request()->url(),
-                         type_hint, &new_type);
-
-  // SniffMimeType() returns false if there is not enough data to determine
-  // the mime type. However, even if it returns false, it returns a new type
-  // that is probably better than the current one.
-  response_->head.mime_type.assign(new_type);
-
-  return made_final_decision;
-}
-
 bool MimeTypeResourceHandler::SelectPluginHandler(bool* defer,
                                                   bool* handled_by_plugin) {
   *handled_by_plugin = false;
@@ -326,7 +199,7 @@ bool MimeTypeResourceHandler::SelectPluginHandler(bool* defer,
   WebPluginInfo plugin;
   bool has_plugin = plugin_service_->GetPluginInfo(
       info->GetChildID(), info->GetRenderFrameID(), info->GetContext(),
-      request()->url(), GURL(), response_->head.mime_type, allow_wildcard,
+      request()->url(), GURL(), response()->head.mime_type, allow_wildcard,
       &stale, &plugin, NULL);
 
   if (stale) {
@@ -350,7 +223,7 @@ bool MimeTypeResourceHandler::SelectPluginHandler(bool* defer,
     plugin_path = plugin.path;
   std::string payload;
   std::unique_ptr<ResourceHandler> handler(host_->MaybeInterceptAsStream(
-      plugin_path, request(), response_.get(), &payload));
+      plugin_path, request(), response(), &payload));
   if (handler) {
     *handled_by_plugin = true;
     return UseAlternateNextHandler(std::move(handler), payload);
@@ -360,10 +233,10 @@ bool MimeTypeResourceHandler::SelectPluginHandler(bool* defer,
 }
 
 bool MimeTypeResourceHandler::SelectNextHandler(bool* defer) {
-  DCHECK(!response_->head.mime_type.empty());
+  DCHECK(!response()->head.mime_type.empty());
 
   ResourceRequestInfoImpl* info = GetRequestInfo();
-  const std::string& mime_type = response_->head.mime_type;
+  const std::string& mime_type = response()->head.mime_type;
 
   // https://crbug.com/568184 - Temporary hack to track servers that aren't
   // setting Content-Disposition when sending x-x509-user-cert and expecting
@@ -372,7 +245,7 @@ bool MimeTypeResourceHandler::SelectNextHandler(bool* defer) {
   if (mime_type == "application/x-x509-user-cert") {
     UMA_HISTOGRAM_BOOLEAN(
         "UserCert.ContentDisposition",
-        response_->head.headers->HasHeader("Content-Disposition"));
+        response()->head.headers->HasHeader("Content-Disposition"));
   }
 
   // Allow requests for object/embed tags to be intercepted as streams.
@@ -419,8 +292,8 @@ bool MimeTypeResourceHandler::SelectNextHandler(bool* defer) {
 bool MimeTypeResourceHandler::UseAlternateNextHandler(
     std::unique_ptr<ResourceHandler> new_handler,
     const std::string& payload_for_old_handler) {
-  if (response_->head.headers.get() &&  // Can be NULL if FTP.
-      response_->head.headers->response_code() / 100 != 2) {
+  if (response()->head.headers.get() &&  // Can be NULL if FTP.
+      response()->head.headers->response_code() / 100 != 2) {
     // The response code indicates that this is an error page, but we don't
     // know how to display the content.  We follow Firefox here and show our
     // own error page instead of triggering a download.
@@ -430,69 +303,9 @@ bool MimeTypeResourceHandler::UseAlternateNextHandler(
     return false;
   }
 
-  // Inform the original ResourceHandler that this will be handled entirely by
-  // the new ResourceHandler.
-  // TODO(darin): We should probably check the return values of these.
-  bool defer_ignored = false;
-  next_handler_->OnResponseStarted(response_.get(), &defer_ignored);
-  // Although deferring OnResponseStarted is legal, the only downstream handler
-  // which does so is CrossSiteResourceHandler. Cross-site transitions should
-  // not trigger when switching handlers.
-  DCHECK(!defer_ignored);
-  if (payload_for_old_handler.empty()) {
-    net::URLRequestStatus status(net::URLRequestStatus::CANCELED,
-                                 net::ERR_ABORTED);
-    next_handler_->OnResponseCompleted(status, std::string(), &defer_ignored);
-    DCHECK(!defer_ignored);
-  } else {
-    scoped_refptr<net::IOBuffer> buf;
-    int size = 0;
-
-    next_handler_->OnWillRead(&buf, &size, -1);
-    CHECK_GE(size, static_cast<int>(payload_for_old_handler.length()));
-
-    memcpy(buf->data(), payload_for_old_handler.c_str(),
-           payload_for_old_handler.length());
-
-    next_handler_->OnReadCompleted(payload_for_old_handler.length(),
-                                   &defer_ignored);
-    DCHECK(!defer_ignored);
+  InstallNewLeafHandler(std::move(new_handler), payload_for_old_handler);
 
-    net::URLRequestStatus status(net::URLRequestStatus::SUCCESS, 0);
-    next_handler_->OnResponseCompleted(status, std::string(), &defer_ignored);
-    DCHECK(!defer_ignored);
-  }
-
-  // This is handled entirely within the new ResourceHandler, so just reset the
-  // original ResourceHandler.
-  next_handler_ = std::move(new_handler);
-  next_handler_->SetController(this);
-
-  return CopyReadBufferToNextHandler();
-}
-
-bool MimeTypeResourceHandler::ReplayReadCompleted(bool* defer) {
-  DCHECK(read_buffer_.get());
-
-  bool result = next_handler_->OnReadCompleted(bytes_read_, defer);
-
-  read_buffer_ = NULL;
-  read_buffer_size_ = 0;
-  bytes_read_ = 0;
-
-  state_ = STATE_STREAMING;
-
-  return result;
-}
-
-void MimeTypeResourceHandler::CallReplayReadCompleted() {
-  bool defer = false;
-  if (!ReplayReadCompleted(&defer)) {
-    controller()->Cancel();
-  } else if (!defer) {
-    state_ = STATE_STREAMING;
-    controller()->Resume();
-  }
+  return true;
 }
 
 bool MimeTypeResourceHandler::MustDownload() {
@@ -508,7 +321,7 @@ bool MimeTypeResourceHandler::MustDownload() {
     must_download_ = true;
   } else if (host_->delegate() &&
              host_->delegate()->ShouldForceDownloadResource(
-                 request()->url(), response_->head.mime_type)) {
+                 request()->url(), response()->head.mime_type)) {
     must_download_ = true;
   } else {
     must_download_ = false;
@@ -517,25 +330,11 @@ bool MimeTypeResourceHandler::MustDownload() {
   return must_download_;
 }
 
-bool MimeTypeResourceHandler::CopyReadBufferToNextHandler() {
-  if (!read_buffer_.get())
-    return true;
-
-  scoped_refptr<net::IOBuffer> buf;
-  int buf_len = 0;
-  if (!next_handler_->OnWillRead(&buf, &buf_len, bytes_read_))
-    return false;
-
-  CHECK((buf_len >= bytes_read_) && (bytes_read_ >= 0));
-  memcpy(buf->data(), read_buffer_->data(), bytes_read_);
-  return true;
-}
-
 void MimeTypeResourceHandler::OnPluginsLoaded(
     const std::vector<WebPluginInfo>& plugins) {
   request()->LogUnblocked();
   bool defer = false;
-  if (!ProcessResponse(&defer)) {
+  if (!ProcessReplay(&defer)) {
     controller()->Cancel();
   } else if (!defer) {
     controller()->Resume();