Add service unittest for WakeLockServiceImpl.

device/power_save_blocker/power_save_blocker_x11.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 <X11/Xlib.h>
 #include <X11/extensions/dpms.h>
 #include <X11/extensions/scrnsaver.h>
 #include <stdint.h>
 
 #include <memory>
@@ skipping 423 matching lines @@
   }
   return enabled;
 }
 
 bool PowerSaveBlocker::Delegate::XSSAvailable() {
   DCHECK(ui_task_runner_->RunsTasksOnCurrentThread());
   // X Screen Saver isn't accessible in headless mode.
   if (base::CommandLine::ForCurrentProcess()->HasSwitch(switches::kHeadless))
     return false;
   XDisplay* display = gfx::GetXDisplay();
+  // In service_unittests context, XDisplay is not well initialized. passing a

[blundell, 2017/05/16 13:37:55]

Did you check whether it's possible to initialize XDisplay instead?

[ke.he, 2017/05/17 07:19:54]

Yes, I followed how the browser_main_runner.cc initializes the x11, calling
gfx::InitialzieThreadedX11(), and the XDisplay can be initialized successfully.
But again powerSaveBlocker crashes on some place related to D-BUS. So, still
complex.

I feel that this unittest is for the WakeLockServiceImpl and its mojo
interfaces, so I stopped digging on why the PowerSaveBlocker doesn't work on
DeviceServiceTestBase. Maybe in future it blocks something, I will continue to
fix it then. Do you think it is OK?

[blundell, 2017/05/17 09:01:42]

Short-circuiting out early in the test isn't concerning; my concern is only that
now we're adding a path for silent failure in production code that wasn't there
before. I think maybe it would be a better to add an OS_LINUX-specific
DisableXSSForTest() method to PowerSaveBlocker?

+  // nullptr to XScreenSaverQueryExtension() will cause crash.
+  if (!display)
+    return false;
   int dummy;
   int major;
   int minor;
 
   if (!XScreenSaverQueryExtension(display, &dummy, &dummy))
     return false;
 
   if (!XScreenSaverQueryVersion(display, &major, &minor))
     return false;
 
@@ skipping 49 matching lines @@
   }
 }
 
 PowerSaveBlocker::~PowerSaveBlocker() {
   delegate_->CleanUp();
   if (freedesktop_suspend_delegate_)
     freedesktop_suspend_delegate_->CleanUp();
 }
 
 }  // namespace device