Fix CheckFalseTest.CheckFails on Linux after my change to ui_test.

chrome/test/ui/ui_test.cc

 // Copyright (c) 2010 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/test/ui/ui_test.h"
 
 #if defined(OS_POSIX)
 #include <signal.h>
 #include <sys/types.h>
 #endif
 
 #include <set>
 #include <vector>
 
 #include "app/sql/connection.h"
 #include "base/base_switches.h"
 #include "base/command_line.h"
+#include "base/environment.h"
 #include "base/file_path.h"
 #include "base/file_util.h"
 #include "base/path_service.h"
 #include "base/platform_thread.h"
 #include "base/process_util.h"
 #include "base/scoped_ptr.h"
 #include "base/scoped_temp_dir.h"
 #include "base/string_number_conversions.h"
 #include "base/test/test_file_util.h"
 #include "base/time.h"
@@ skipping 379 matching lines @@
 void UITestBase::LaunchBrowser(const CommandLine& arguments,
                                bool clear_profile) {
   if (clear_profile || !temp_profile_dir_->IsValid()) {
     temp_profile_dir_.reset(new ScopedTempDir());
     ASSERT_TRUE(temp_profile_dir_->CreateUniqueTempDir());
 
     // Update the information about user data directory location on the ui_test
     // side. Using PathService seems to be the most reliable, consistent way
     // to do that.
     ASSERT_TRUE(PathService::Override(chrome::DIR_USER_DATA, user_data_dir()));
+
+#if defined(OS_LINUX)
+    // Make sure the cache directory is inside our clear profile. Otherwise
+    // the cache may contain data from earlier tests that could break the
+    // current test.
+    //
+    // Note: we use an environment variable here, because we have to pass the
+    // value to the child process. This is the simplest way to do it.
+    scoped_ptr<base::Environment> env(base::Environment::Create());
+    env->SetVar("XDG_CACHE_HOME", user_data_dir().value());
+#endif
   }
 
   if (!template_user_data_.empty()) {
     // Recursively copy the template directory to the user_data_dir.
     ASSERT_TRUE(file_util::CopyRecursiveDirNoCache(
         template_user_data_,
         user_data_dir()));
     // If we're using the complex theme data, we need to write the
     // user_data_dir_ to our preferences file.
     if (profile_type_ == UITestBase::COMPLEX_THEME) {
@@ skipping 829 matching lines @@
   UITestBase::TearDown();
   PlatformTest::TearDown();
 }
 
 AutomationProxy* UITest::CreateAutomationProxy(int execution_timeout) {
   // Make the AutomationProxy disconnect the channel on the first error,
   // so that we avoid spending a lot of time in timeouts. The browser is likely
   // hosed if we hit those errors.
   return new AutomationProxy(execution_timeout, true);
 }