content_shell/app_shell: validate --data-path and fall back to default directory

content/shell/browser/shell_browser_context.cc

 // Copyright 2013 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/shell/browser/shell_browser_context.h"
 
 #include <utility>
 
 #include "base/bind.h"
 #include "base/command_line.h"
@@ skipping 57 matching lines @@
       BrowserThread::IO, FROM_HERE, resource_context_.release());
   }
 }
 
 void ShellBrowserContext::InitWhileIOAllowed() {
   base::CommandLine* cmd_line = base::CommandLine::ForCurrentProcess();
   if (cmd_line->HasSwitch(switches::kIgnoreCertificateErrors))
     ignore_certificate_errors_ = true;
   if (cmd_line->HasSwitch(switches::kContentShellDataPath)) {
     path_ = cmd_line->GetSwitchValuePath(switches::kContentShellDataPath);
-    BrowserContext::Initialize(this, path_);
-    return;
+    if (base::DirectoryExists(path_) || base::CreateDirectory(path_))  {
+      // We need to have an absolute path.

[Peter Beverloo, 2016/09/29 16:22:53]

nit: might be good to document that the PathService normally takes care of this,
and features therefore might assume this to be the case.

[michaelpg, 2016/09/30 03:38:56]

Done.

+      if (!path_.IsAbsolute())
+        path_ = base::MakeAbsoluteFilePath(path_);
+      if (!path_.empty()) {
+        BrowserContext::Initialize(this, path_);
+        return;
+      }
+    } else {
+      LOG(WARNING) << "Unable to create data-path directory: " << path_.value();
+    }
   }
+
 #if defined(OS_WIN)
   CHECK(PathService::Get(base::DIR_LOCAL_APP_DATA, &path_));
   path_ = path_.Append(std::wstring(L"content_shell"));
 #elif defined(OS_LINUX)
   std::unique_ptr<base::Environment> env(base::Environment::Create());
   base::FilePath config_dir(
       base::nix::GetXDGDirectory(env.get(),
                                  base::nix::kXdgConfigHomeEnvVar,
                                  base::nix::kDotConfigDir));
   path_ = config_dir.Append("content_shell");
@@ skipping 104 matching lines @@
   return permission_manager_.get();
 }
 
 BackgroundSyncController* ShellBrowserContext::GetBackgroundSyncController() {
   if (!background_sync_controller_)
     background_sync_controller_.reset(new MockBackgroundSyncController());
   return background_sync_controller_.get();
 }
 
 }  // namespace content