media: Add helper function to register pepper CDMs

chrome/browser/media/pepper_cdm_test_helper.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 "chrome/browser/media/pepper_cdm_test_helper.h"
+
+#include "base/command_line.h"
+#include "base/files/file_util.h"
+#include "base/path_service.h"
+#include "base/strings/utf_string_conversions.h"
+#include "content/public/common/content_switches.h"
+
+#include "widevine_cdm_version.h"  //  In SHARED_INTERMEDIATE_DIR.
+
+const char kClearKeyCdmAdapterFileName[] =
+#if defined(OS_MACOSX)
+    "clearkeycdmadapter.plugin";
+#elif defined(OS_WIN)
+    "clearkeycdmadapter.dll";
+#elif defined(OS_POSIX)
+    "libclearkeycdmadapter.so";
+#endif
+
+const char kClearKeyCdmPepperMimeType[] = "application/x-ppapi-clearkey-cdm";
+
+base::FilePath::StringType BuildPepperCdmRegistration(
+    const std::string& adapter_file_name,
+    const std::string& mime_type,
+    bool expect_adapter_exists) {
+  base::FilePath adapter_path;
+  DCHECK(PathService::Get(base::DIR_MODULE, &adapter_path));

[Lei Zhang, 2016/05/18 00:53:11]

Can't put this in a DCHECK. It won't run in release builds.

[xhwang, 2016/05/18 02:08:10]

Good catch. It's really not interesting to check this. Dropped the DCHECK.

+  adapter_path = adapter_path.AppendASCII(adapter_file_name);
+  DCHECK_EQ(expect_adapter_exists, base::PathExists(adapter_path));
+
+  base::FilePath::StringType pepper_cdm_registration = adapter_path.value();

[Lei Zhang, 2016/05/18 00:53:11]

If this is just a base::FilePath, then you can use AppendASCII() below and you
won't need the ifdef.

[xhwang, 2016/05/18 02:08:10]

The registration is a string. AppendASCII will add delimiters like "/" that
won't work here.

+  pepper_cdm_registration.append(FILE_PATH_LITERAL("#CDM#0.1.0.0;"));
+
+#if defined(OS_WIN)
+  pepper_cdm_registration.append(base::ASCIIToUTF16(mime_type));
+#else
+  pepper_cdm_registration.append(mime_type);
+#endif
+
+  return pepper_cdm_registration;
+}
+
+void RegisterPepperCdm(base::CommandLine* command_line,
+                       const std::string& adapter_file_name,
+                       const std::string& mime_type,
+                       bool expect_adapter_exists) {
+  base::FilePath::StringType pepper_cdm_registration =
+      BuildPepperCdmRegistration(adapter_file_name, mime_type,
+                                 expect_adapter_exists);
+
+  // Append the switch to register the CDM Adapter.
+  command_line->AppendSwitchNative(switches::kRegisterPepperPlugins,
+                                   pepper_cdm_registration);
+}