Reland of "Implements content_decoder_tool.cc to decode offline any resources."

TBR=gavinp@chromium.org
BUG=582080

> Revert of Implement content_decoder_tool.cc to decode offline any resources. (patchset #4 id:60001 of https://codereview.chromium.org/1767653002/ )
>
> Reason for revert:
> Broke iOS build: https://build.chromium.org/p/chromium.mac/builders/iOS_Device/builds/44002
>
> Original issue's description:
> > Implement content_decoder_tool.cc to decode offline any resources.
> >
> > Sandwich is going to use the HTMLPreloadScanner to get all the
> > resources to prefetch instead of using the Clovis' dependency
> > graph. However resources in the chrome HTTP cache or in the WPR
> > archive are stored as transport layer content, implying that they
> > might be stored using a compression algorithm, according to the
> > Content-Encoding response header.
> >
> > This tools enable us to decode any resources using the same very
> > code path used in chrome, implying that we will be able to
> > uncompressed absolutely all resources that chrome can and is
> > advertising in its Accept-Encoding request header.
> >
> > BUG=582080
> >
> > Committed: https://crrev.com/4dc1dc6668a87620574dd43392046c3691914da2
> > Cr-Commit-Position: refs/heads/master@{#382599}

Review URL: https://codereview.chromium.org/1831433002

Cr-Commit-Position: refs/heads/master@{#382831}

2 files changed, 99 insertions, 0 deletions

diff --git a/net/net.gyp b/net/net.gyp
index 661a019..c50c4f6 100644
--- a/net/net.gyp
+++ b/net/net.gyp
@@ -1691,6 +1691,22 @@
         },
       ],
     }],
+    ['OS == "linux"', {
+      'targets': [
+        {
+          'target_name': 'content_decoder_tool',
+          'type': 'executable',
+          'dependencies': [
+            '../base/base.gyp:base',
+            'net',
+          ],
+          'sources': [
+            'tools/content_decoder_tool/content_decoder_tool.cc',
+            'filter/mock_filter_context.cc',
+          ],
+        }
+      ],
+    }],
     ['test_isolation_mode != "noop"', {
       'targets': [
         {
diff --git a/net/tools/content_decoder_tool/content_decoder_tool.cc b/net/tools/content_decoder_tool/content_decoder_tool.cc
new file mode 100644
index 0000000..0eae255
--- /dev/null
+++ b/net/tools/content_decoder_tool/content_decoder_tool.cc
@@ -0,0 +1,83 @@
+// 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 <iostream>
+
+#include "base/command_line.h"
+#include "net/base/io_buffer.h"
+#include "net/filter/filter.h"
+#include "net/filter/mock_filter_context.h"
+
+using net::Filter;
+
+namespace {
+
+// Print the command line help.
+void PrintHelp(const char* command_line_name) {
+  std::cout << command_line_name << " content_encoding [content_encoding]..."
+            << std::endl
+            << std::endl;
+  std::cout << "Decodes the stdin into the stdout using an content_encoding "
+            << "list given in arguments. This list is expected to be the "
+            << "Content-Encoding HTTP response header's value split by ','."
+            << std::endl;
+}
+
+}  // namespace
+
+int main(int argc, char* argv[]) {
+  base::CommandLine::Init(argc, argv);
+  const base::CommandLine& command_line =
+      *base::CommandLine::ForCurrentProcess();
+
+  std::vector<std::string> content_encodings = command_line.GetArgs();
+  if (content_encodings.size() == 0) {
+    PrintHelp(argv[0]);
+    return 1;
+  }
+
+  std::vector<Filter::FilterType> filter_types;
+  for (const auto& content_encoding : content_encodings) {
+    Filter::FilterType filter_type =
+        Filter::ConvertEncodingToType(content_encoding);
+    if (filter_type == Filter::FILTER_TYPE_UNSUPPORTED) {
+      std::cerr << "Unsupported decoder '" << content_encoding << "'."
+                << std::endl;
+      return 1;
+    }
+    filter_types.push_back(filter_type);
+  }
+
+  net::MockFilterContext filter_context;
+  scoped_ptr<Filter> filter(Filter::Factory(filter_types, filter_context));
+  if (!filter) {
+    std::cerr << "Couldn't create the decoder." << std::endl;
+    return 1;
+  }
+
+  net::IOBuffer* pre_filter_buf = filter->stream_buffer();
+  int pre_filter_buf_len = filter->stream_buffer_size();
+  while (std::cin) {
+    std::cin.read(pre_filter_buf->data(), pre_filter_buf_len);
+    int pre_filter_data_len = std::cin.gcount();
+    filter->FlushStreamBuffer(pre_filter_data_len);
+
+    while (true) {
+      const int kPostFilterBufLen = 4096;
+      char post_filter_buf[kPostFilterBufLen];
+      int post_filter_data_len = kPostFilterBufLen;
+      Filter::FilterStatus filter_status =
+          filter->ReadData(post_filter_buf, &post_filter_data_len);
+      std::cout.write(post_filter_buf, post_filter_data_len);
+      if (filter_status == Filter::FILTER_ERROR) {
+        std::cerr << "Couldn't decode stdin." << std::endl;
+        return 1;
+      } else if (filter_status != Filter::FILTER_OK) {
+        break;
+      }
+    }
+  }
+
+  return 0;
+}