Update MimeSniffingResourceHandler tests to use MockResourceLoader.

content/browser/loader/test_resource_handler.cc

 // Copyright 2016 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "content/browser/loader/test_resource_handler.h"
 
 #include "base/logging.h"
 #include "content/browser/loader/resource_controller.h"
 #include "content/public/common/resource_response.h"
 #include "testing/gtest/include/gtest/gtest.h"
@@ skipping 114 matching lines @@
 bool TestResourceHandler::OnWillRead(scoped_refptr<net::IOBuffer>* buf,
                                      int* buf_size,
                                      int min_size) {
   EXPECT_FALSE(canceled_);
   EXPECT_FALSE(expect_on_data_downloaded_);
   EXPECT_EQ(0, on_response_completed_called_);
   ScopedCallDepthTracker call_depth_tracker(&call_depth_);
 
   ++on_will_read_called_;
 
-  *buf = buffer_;
-  *buf_size = buffer_size_;
-  memset(buffer_->data(), '\0', buffer_size_);
-  if (!on_will_read_result_)
+  if (!on_will_read_result_) {
     canceled_ = true;
+  } else {
+    *buf = buffer_;
+    *buf_size = buffer_size_;
+    memset(buffer_->data(), '\0', buffer_size_);

[mmenke, 2017/01/10 19:20:34]

This change is to meet MockResourceLoader's expectation that these aren't set on
error (Which seems like a good idea to me...But then, I wrote that check)

+  }
+
   return on_will_read_result_;
 }
 
 bool TestResourceHandler::OnReadCompleted(int bytes_read, bool* defer) {
   EXPECT_FALSE(canceled_);
   EXPECT_FALSE(expect_on_data_downloaded_);
   EXPECT_EQ(1, on_will_start_called_);
   EXPECT_EQ(1, on_response_started_called_);
   EXPECT_EQ(0, on_response_completed_called_);
   EXPECT_EQ(0, on_read_eof_);
@@ skipping 71 matching lines @@
 void TestResourceHandler::WaitUntilDeferred() {
   deferred_run_loop_->Run();
   deferred_run_loop_.reset(new base::RunLoop());
 }
 
 void TestResourceHandler::WaitUntilResponseComplete() {
   response_complete_run_loop_.Run();
 }
 
 }  // namespace content