Add buffering to MimeSniffingResourceHandler.

content/browser/loader/mojo_async_resource_handler.cc

Index: content/browser/loader/mojo_async_resource_handler.cc
diff --git a/content/browser/loader/mojo_async_resource_handler.cc b/content/browser/loader/mojo_async_resource_handler.cc
index 48b668609b260afeae549dac87a897cab4c4e37d..d8b4bc89a5a9dbc88899f84448491f2e7a1f1ce9 100644
--- a/content/browser/loader/mojo_async_resource_handler.cc
+++ b/content/browser/loader/mojo_async_resource_handler.cc
@@ -28,7 +28,6 @@
 #include "content/public/common/resource_response.h"
 #include "mojo/public/c/system/data_pipe.h"
 #include "mojo/public/cpp/bindings/message.h"
-#include "net/base/mime_sniffer.h"
 #include "net/base/net_errors.h"
 #include "net/url_request/redirect_info.h"
 
@@ -37,11 +36,6 @@ namespace {
 
 int g_allocation_size = MojoAsyncResourceHandler::kDefaultAllocationSize;
 
-// MimeTypeResourceHandler *implicitly* requires that the buffer size
-// returned from OnWillRead should be larger than certain size.
-// TODO(yhirano): Fix MimeTypeResourceHandler.
-constexpr size_t kMinAllocationSize = 2 * net::kMaxBytesToSniff;
-
 constexpr size_t kMaxChunkSize = 32 * 1024;
 
 void GetNumericArg(const std::string& name, int* result) {
@@ -238,9 +232,7 @@ void MojoAsyncResourceHandler::OnWillRead(
     return;
   }
 
-  bool first_call = false;
   if (!shared_writer_) {
-    first_call = true;
     MojoCreateDataPipeOptions options;
     options.struct_size = sizeof(MojoCreateDataPipeOptions);
     options.flags = MOJO_CREATE_DATA_PIPE_OPTIONS_FLAG_NONE;
@@ -275,20 +267,6 @@ void MojoAsyncResourceHandler::OnWillRead(
     return;
   }
 
-  // The first call to OnWillRead must return a buffer of at least
-  // kMinAllocationSize. If the Mojo buffer is too small, need to allocate an
-  // intermediary buffer.
-  if (first_call && static_cast<size_t>(buffer_->size()) < kMinAllocationSize) {
-    // The allocated buffer is too small, so need to create an intermediary one.
-    if (EndWrite(0) != MOJO_RESULT_OK) {
-      controller->CancelWithError(net::ERR_INSUFFICIENT_RESOURCES);
-      return;
-    }
-    DCHECK(!is_using_io_buffer_not_from_writer_);
-    is_using_io_buffer_not_from_writer_ = true;
-    buffer_ = new net::IOBufferWithSize(kMinAllocationSize);
-  }
-
   *buf = buffer_;
   *buf_size = buffer_->size();
   controller->Resume();
@@ -322,25 +300,6 @@ void MojoAsyncResourceHandler::OnReadCompleted(
     response_body_consumer_handle_.reset();
   }
 
-  if (is_using_io_buffer_not_from_writer_) {
-    // Couldn't allocate a large enough buffer on the data pipe in OnWillRead.
-    DCHECK_EQ(0u, buffer_bytes_read_);
-    buffer_bytes_read_ = bytes_read;
-    bool defer = false;
-    if (!CopyReadDataToDataPipe(&defer)) {
-      controller->CancelWithError(net::ERR_INSUFFICIENT_RESOURCES);
-      return;
-    }
-    if (defer) {
-      request()->LogBlockedBy("MojoAsyncResourceHandler");
-      did_defer_on_writing_ = true;
-      HoldController(std::move(controller));
-      return;
-    }
-    controller->Resume();
-    return;
-  }
-
   if (EndWrite(bytes_read) != MOJO_RESULT_OK) {
     controller->Cancel();
     return;
@@ -367,7 +326,6 @@ void MojoAsyncResourceHandler::FollowRedirect() {
   }
 
   DCHECK(!did_defer_on_will_read_);
-  DCHECK(!did_defer_on_writing_);
   did_defer_on_redirect_ = false;
   request()->LogUnblocked();
   Resume();
@@ -457,30 +415,6 @@ void MojoAsyncResourceHandler::OnResponseCompleted(
   controller->Resume();
 }
 
-bool MojoAsyncResourceHandler::CopyReadDataToDataPipe(bool* defer) {
-  while (buffer_bytes_read_ > 0) {
-    scoped_refptr<net::IOBufferWithSize> dest;
-    if (!AllocateWriterIOBuffer(&dest, defer))
-      return false;
-    if (*defer)
-      return true;
-
-    size_t copied_size =
-        std::min(buffer_bytes_read_, static_cast<size_t>(dest->size()));
-    memcpy(dest->data(), buffer_->data() + buffer_offset_, copied_size);
-    buffer_offset_ += copied_size;
-    buffer_bytes_read_ -= copied_size;
-    if (EndWrite(copied_size) != MOJO_RESULT_OK)
-      return false;
-  }
-
-  // All bytes are copied.
-  buffer_ = nullptr;
-  buffer_offset_ = 0;
-  is_using_io_buffer_not_from_writer_ = false;
-  return true;
-}
-
 bool MojoAsyncResourceHandler::AllocateWriterIOBuffer(
     scoped_refptr<net::IOBufferWithSize>* buf,
     bool* defer) {
@@ -510,44 +444,21 @@ bool MojoAsyncResourceHandler::CheckForSufficientResource() {
 }
 
 void MojoAsyncResourceHandler::OnWritable(MojoResult result) {
-  if (did_defer_on_will_read_) {
-    DCHECK(has_controller());
-    DCHECK(!did_defer_on_writing_);
-    DCHECK(!did_defer_on_redirect_);
-
-    did_defer_on_will_read_ = false;
-
-    scoped_refptr<net::IOBuffer>* parent_buffer = parent_buffer_;
-    parent_buffer_ = nullptr;
-    int* parent_buffer_size = parent_buffer_size_;
-    parent_buffer_size_ = nullptr;
-
-    request()->LogUnblocked();
-    OnWillRead(parent_buffer, parent_buffer_size, ReleaseController());
+  if (!did_defer_on_will_read_)
     return;
-  }
 
-  if (!did_defer_on_writing_)
-    return;
   DCHECK(has_controller());
   DCHECK(!did_defer_on_redirect_);
-  did_defer_on_writing_ = false;
-
-  DCHECK(is_using_io_buffer_not_from_writer_);
-  // |buffer_| is set to a net::IOBufferWithSize. Write the buffer contents
-  // to the data pipe.
-  DCHECK_GT(buffer_bytes_read_, 0u);
-  if (!CopyReadDataToDataPipe(&did_defer_on_writing_)) {
-    CancelWithError(net::ERR_INSUFFICIENT_RESOURCES);
-    return;
-  }
 
-  if (did_defer_on_writing_) {
-    // Continue waiting.
-    return;
-  }
+  did_defer_on_will_read_ = false;
+
+  scoped_refptr<net::IOBuffer>* parent_buffer = parent_buffer_;
+  parent_buffer_ = nullptr;
+  int* parent_buffer_size = parent_buffer_size_;
+  parent_buffer_size_ = nullptr;
+
   request()->LogUnblocked();
-  Resume();
+  OnWillRead(parent_buffer, parent_buffer_size, ReleaseController());
 }
 
 void MojoAsyncResourceHandler::Cancel() {