Don't depend on X11 when rtc_use_x11=false.

This CL makes X11 optional for audio_device_pulse_linux.
Apply the same guards than for audio_device_alsa_linux.
Cf commit 75f18fca8eef7c27073923c46ff73be5ba0e0491.

Bug: webrtc:9569
Change-Id: Iaddbfb62112c504531376bad0db8f04caa4350c7
Reviewed-on: https://webrtc-review.googlesource.com/93030
Reviewed-by: Mirko Bonadei <mbonadei@webrtc.org>
Reviewed-by: Patrik Höglund <phoglund@webrtc.org>
Commit-Queue: Yves Gerey <yvesg@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#24274}
diff --git a/modules/audio_device/linux/audio_device_pulse_linux.cc b/modules/audio_device/linux/audio_device_pulse_linux.cc
index 7dda66f..2f343ba 100644
--- a/modules/audio_device/linux/audio_device_pulse_linux.cc
+++ b/modules/audio_device/linux/audio_device_pulse_linux.cc
@@ -155,12 +155,14 @@
     return InitStatus::OTHER_ERROR;
   }
 
+#if defined(WEBRTC_USE_X11)
   // Get X display handle for typing detection
   _XDisplay = XOpenDisplay(NULL);
   if (!_XDisplay) {
     RTC_LOG(LS_WARNING)
         << "failed to open X display, typing detection will not work";
   }
+#endif
 
   // RECORDING
   _ptrThreadRec.reset(new rtc::PlatformThread(
@@ -212,10 +214,12 @@
     return -1;
   }
 
+#if defined(WEBRTC_USE_X11)
   if (_XDisplay) {
     XCloseDisplay(_XDisplay);
     _XDisplay = NULL;
   }
+#endif
 
   _initialized = false;
   _outputDeviceIsSpecified = false;
@@ -2280,6 +2284,7 @@
 }
 
 bool AudioDeviceLinuxPulse::KeyPressed() const {
+#if defined(WEBRTC_USE_X11)
   char szKey[32];
   unsigned int i = 0;
   char state = 0;
@@ -2297,5 +2302,8 @@
   // Save old state
   memcpy((char*)_oldKeyState, (char*)szKey, sizeof(_oldKeyState));
   return (state != 0);
+#else
+  return false;
+#endif
 }
 }  // namespace webrtc
diff --git a/modules/audio_device/linux/audio_device_pulse_linux.h b/modules/audio_device/linux/audio_device_pulse_linux.h
index d16c13f..854c7c6 100644
--- a/modules/audio_device/linux/audio_device_pulse_linux.h
+++ b/modules/audio_device/linux/audio_device_pulse_linux.h
@@ -19,7 +19,10 @@
 #include "rtc_base/platform_thread.h"
 #include "rtc_base/thread_checker.h"
 
+#if defined(WEBRTC_USE_X11)
 #include <X11/Xlib.h>
+#endif
+
 #include <pulse/pulseaudio.h>
 
 // We define this flag if it's missing from our headers, because we want to be
@@ -328,7 +331,9 @@
   pa_buffer_attr _recBufferAttr;
 
   char _oldKeyState[32];
+#if defined(WEBRTC_USE_X11)
   Display* _XDisplay;
+#endif
 };
 
 }  // namespace webrtc