Add flags entries to test chrome OS component updates in release mode.

chrome/common/chrome_content_client.cc

 // Copyright (c) 2012 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/common/chrome_content_client.h"
 
 #include <stdint.h>
 
 #include <map>
 #include <memory>
 #include <tuple>
 
 #include "base/command_line.h"
 #include "base/debug/crash_logging.h"
 #include "base/files/file_util.h"
 #include "base/json/json_reader.h"
 #include "base/memory/ptr_util.h"
 #include "base/native_library.h"
 #include "base/path_service.h"
 #include "base/strings/string16.h"
 #include "base/strings/string_number_conversions.h"
 #include "base/strings/string_split.h"
 #include "base/strings/string_util.h"
 #include "base/strings/stringprintf.h"
 #include "base/strings/utf_string_conversions.h"
 #include "build/build_config.h"
 #include "chrome/common/child_process_logging.h"
 #include "chrome/common/chrome_constants.h"
+#include "chrome/common/chrome_features.h"
 #include "chrome/common/chrome_paths.h"
 #include "chrome/common/chrome_switches.h"
 #include "chrome/common/crash_keys.h"
 #include "chrome/common/pepper_flash.h"
 #include "chrome/common/secure_origin_whitelist.h"
 #include "chrome/common/url_constants.h"
 #include "chrome/grit/common_resources.h"
 #include "components/dom_distiller/core/url_constants.h"
 #include "components/version_info/version_info.h"
 #include "content/public/common/cdm_info.h"
@@ skipping 453 matching lines @@
 
 // Get component updated flash for desktop Linux and Chrome OS.
 #if defined(OS_LINUX)
   // Depending on the sandbox configuration, the file system
   // is not always available. If it is not available, do not try and load any
   // flash plugin. The flash player, if any, preloaded before the sandbox
   // initialization will continue to be used.
   if (!sandbox::Credentials::HasFileSystemAccess())
     return;
 
+#if defined(OS_CHROMEOS)
+  // On Chrome OS, we cannot test component flash updates reliably unless we
+  // guarantee that the component updated flash plugin will be used.
+  if (base::FeatureList::IsEnabled(features::kComponentFlashOnly)) {
+    auto component_flash = base::MakeUnique<content::PepperPluginInfo>();
+    if (GetComponentUpdatedPepperFlash(component_flash.get())) {
+      plugins->push_back(*component_flash);
+    }
+    return;

[waffles, 2016/12/01 23:51:18]

I think it might be cleaner to instead do something like:

#if defined(OS_CHROMEOS)
if (base::FeatureList::IsEnabled(features::kComponentFlashOnly))
  return;
#endif

in the body of GetCommandLinePepperFlash, what do you think?

I agree it puts this override less front-and-center, but in practice
SystemPepperFlash doesn't exist on Linux, and I'm slightly worried about
short-circuiting the "fake Flash plugin" if  GetComponentUpdatedPepperFlash
returns false.

[Greg K, 2016/12/02 01:06:26]

I think you're right. The override is less obvious, but also much less prone to
break things.

+  }
+#endif  // defined(OS_CHROMEOS)
+
   auto component_flash = base::MakeUnique<content::PepperPluginInfo>();
   if (GetComponentUpdatedPepperFlash(component_flash.get()))
     flash_versions.push_back(std::move(component_flash));
 #endif  // defined(OS_LINUX)
 
   auto command_line_flash = base::MakeUnique<content::PepperPluginInfo>();
   if (GetCommandLinePepperFlash(command_line_flash.get()))
     flash_versions.push_back(std::move(command_line_flash));
 
   auto system_flash = base::MakeUnique<content::PepperPluginInfo>();
@@ skipping 174 matching lines @@
   if (!origin_trial_policy_)
     origin_trial_policy_ = base::MakeUnique<ChromeOriginTrialPolicy>();
   return origin_trial_policy_.get();
 }
 
 #if defined(OS_ANDROID)
 media::MediaClientAndroid* ChromeContentClient::GetMediaClientAndroid() {
   return new ChromeMediaClientAndroid();
 }
 #endif  // OS_ANDROID