Add a flag to dump IPC messages sent from the renderer to the browser.

chrome/common/external_ipc_dumper.cc

+// Copyright (c) 2015 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 "base/files/file_path.h"
+#include "base/logging.h"
+#include "base/native_library.h"
+#include "base/path_service.h"
+#include "chrome/common/external_ipc_dumper.h"
+
+typedef IPC::ChannelProxy::OutgoingMessageFilter* (*GetFilterFunction)();
+typedef void (*SetDumpDirectoryFunction)(const base::FilePath&);
+
+const char kFilterEntryName[] = "GetFilter";
+const char kSetDumpDirectoryEntryName[] = "SetDumpDirectory";
+
+#if defined(OS_WIN)
+#define IPC_MESSAGE_DUMP_MODULE FILE_PATH_LITERAL("ipc_message_dump.dll")
+#else
+#define IPC_MESSAGE_DUMP_MODULE FILE_PATH_LITERAL("libipc_message_dump.so")
+#endif
+
+IPC::ChannelProxy::OutgoingMessageFilter* LoadExternalIPCDumper(
+    const base::FilePath& dump_directory) {
+  IPC::ChannelProxy::OutgoingMessageFilter* result = NULL;
+
+  base::FilePath module_path;
+  if (!PathService::Get(base::DIR_MODULE, &module_path)) {
+    LOG(ERROR) << "Unable to get message dump module directory.";
+    return result;
+  }
+
+  base::FilePath library_path = module_path.Append(IPC_MESSAGE_DUMP_MODULE);
+  base::NativeLibraryLoadError load_error;
+  base::NativeLibrary library =
+      base::LoadNativeLibrary(library_path, &load_error);
+
+  if (!library) {
+    LOG(ERROR) << load_error.ToString();
+    return result;
+  }
+
+  SetDumpDirectoryFunction set_directory_entry_point =
+      reinterpret_cast<SetDumpDirectoryFunction>(
+          base::GetFunctionPointerFromNativeLibrary(
+              library, kSetDumpDirectoryEntryName));
+  if (set_directory_entry_point)
+    set_directory_entry_point(dump_directory);
+  else
+    LOG(ERROR) << kSetDumpDirectoryEntryName

[inferno, 2015/03/05 22:54:52]

else needs { }. or better way is to follow the same "if (!" and return result on
error.

+               << " not exported by message dump module.";
+
+  GetFilterFunction filter_entry_point = reinterpret_cast<GetFilterFunction>(
+      base::GetFunctionPointerFromNativeLibrary(library, kFilterEntryName));
+  if (filter_entry_point)
+    result = filter_entry_point();
+  else
+    LOG(ERROR) << kFilterEntryName << " not exported by message dump module.";

[inferno, 2015/03/05 22:54:52]

or better way is to follow the same "if (!" and return result on

+
+  return result;
+}