Remove requirement that mojo::Environment be instantiated.

mojo/public/cpp/environment/tests/logging_unittest.cc

 // Copyright 2014 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 <stdlib.h>
 
 #include <sstream>
 #include <string>
 
 #include "mojo/public/cpp/environment/environment.h"
@@ skipping 12 matching lines @@
   int member;
 };
 
 bool DcheckTestHelper(bool* was_called) {
   *was_called = true;
   return false;
 }
 
 class LoggingTest : public testing::Test {
  public:
-  LoggingTest() : environment_(nullptr, &kMockLogger) {
+  LoggingTest() {
+    Environment::SetDefaultLogger(&kMockLogger);
     minimum_log_level_ = MOJO_LOG_LEVEL_INFO;
     ResetMockLogger();
   }
   ~LoggingTest() override {}
 
  protected:
   // Note: Does not reset |minimum_log_level_|.
   static void ResetMockLogger() {
     log_message_was_called_ = false;
     last_log_level_ = MOJO_LOG_LEVEL_INFO;
@@ skipping 31 matching lines @@
     last_source_line_ = source_line;
     last_message_ = message;
   }
 
   static MojoLogLevel MockGetMinimumLogLevel() { return minimum_log_level_; }
 
   static void MockSetMinimumLogLevel(MojoLogLevel minimum_log_level) {
     minimum_log_level_ = minimum_log_level;
   }
 
-  Environment environment_;
-
   static const MojoLogger kMockLogger;
   static MojoLogLevel minimum_log_level_;
   static bool log_message_was_called_;
   static MojoLogLevel last_log_level_;
   static std::string last_source_file_;
   static uint32_t last_source_line_;
   static std::string last_message_;
   static bool not_called_condition_was_called_;
 
   MOJO_DISALLOW_COPY_AND_ASSIGN(LoggingTest);
@@ skipping 415 matching lines @@
   ResetMockLogger();
 
   // Also try to make sure that we parenthesize the condition properly.
   bool x = true;
   MOJO_DCHECK(false || x) << "hello";
   EXPECT_FALSE(log_message_was_called());
 }
 
 }  // namespace
 }  // namespace mojo