Revert of media: Simplify CdmHostFile(s)

content/common/media/cdm_host_file.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/common/media/cdm_host_file.h"
 
 #include <memory>
 
 #include "base/command_line.h"
 #include "base/feature_list.h"
 #include "base/logging.h"
 #include "base/memory/ptr_util.h"
+#include "media/base/media_switches.h"
 #include "media/cdm/api/content_decryption_module_ext.h"
 
 namespace content {
 
+namespace {
+
+bool IgnoreMissingCdmHostFile() {
+  return base::CommandLine::ForCurrentProcess()->HasSwitch(
+      switches::kIgnoreMissingCdmHostFile);
+}
+
+}  // namespace
+
 // static
 std::unique_ptr<CdmHostFile> CdmHostFile::Create(
     const base::FilePath& file_path,
     const base::FilePath& sig_file_path) {
-  DVLOG(1) << __func__;
-
   // Open file at |file_path|.
   base::File file(file_path, base::File::FLAG_OPEN | base::File::FLAG_READ);
-  DVLOG(1) << "  " << file.IsValid() << ": " << file_path.MaybeAsASCII();
+  if (!file.IsValid()) {
+    DVLOG(1) << "Failed to open file at " << file_path.MaybeAsASCII();
+    return nullptr;
+  }
 
   // Also open the sig file at |sig_file_path|.
   base::File sig_file(sig_file_path,
                       base::File::FLAG_OPEN | base::File::FLAG_READ);
-  DVLOG(1) << "  " << sig_file.IsValid() << ": "
-           << sig_file_path.MaybeAsASCII();
+  if (!sig_file.IsValid()) {
+    DVLOG(1) << "Failed to open sig file at " << sig_file_path.MaybeAsASCII();
+    if (!IgnoreMissingCdmHostFile())
+      return nullptr;
+
+    DVLOG(1) << "Ignoring sig file failure at " << sig_file_path.MaybeAsASCII();
+  }
 
   return std::unique_ptr<CdmHostFile>(
       new CdmHostFile(file_path, std::move(file), std::move(sig_file)));
 }
 
 cdm::HostFile CdmHostFile::TakePlatformFile() {
   return cdm::HostFile(file_path_.value().c_str(), file_.TakePlatformFile(),
                        sig_file_.TakePlatformFile());
 }
 
 CdmHostFile::CdmHostFile(const base::FilePath& file_path,
                          base::File file,
                          base::File sig_file)
     : file_path_(file_path),
       file_(std::move(file)),
       sig_file_(std::move(sig_file)) {
-  DCHECK(!file_path_.empty());
+  DVLOG(1) << __func__ << ": " << file_path_.value();
+  DCHECK(!file_path_.empty()) << "File path is empty.";
+  DCHECK(file_.IsValid()) << "Invalid file.";
+
+  if (!IgnoreMissingCdmHostFile())
+    DCHECK(sig_file_.IsValid()) << "Invalid signature file.";
 }
 
 }  // namespace content