Revert 7145 "Stop building talk/sound since it is no longer used."

> Stop building talk/sound since it is no longer used.
> 
> BUG=N/A
> R=pbos@webrtc.org
> 
> Review URL: https://webrtc-codereview.appspot.com/22319004

TBR=henrike@webrtc.org

Review URL: https://webrtc-codereview.appspot.com/22619004

git-svn-id: http://webrtc.googlecode.com/svn/trunk@7148 4adac7df-926f-26a2-2b94-8c16560cd09d
diff --git a/talk/libjingle.gyp b/talk/libjingle.gyp
index bb7b3b0..1690cf8 100755
--- a/talk/libjingle.gyp
+++ b/talk/libjingle.gyp
@@ -400,6 +400,48 @@
       ],
     },  # target libjingle
     {
+      'target_name': 'libjingle_sound',
+      'type': 'static_library',
+      'dependencies': [
+        'libjingle',
+      ],
+      'sources': [
+        'sound/automaticallychosensoundsystem.h',
+        'sound/nullsoundsystem.cc',
+        'sound/nullsoundsystem.h',
+        'sound/nullsoundsystemfactory.cc',
+        'sound/nullsoundsystemfactory.h',
+        'sound/platformsoundsystem.cc',
+        'sound/platformsoundsystem.h',
+        'sound/platformsoundsystemfactory.cc',
+        'sound/platformsoundsystemfactory.h',
+        'sound/sounddevicelocator.h',
+        'sound/soundinputstreaminterface.h',
+        'sound/soundoutputstreaminterface.h',
+        'sound/soundsystemfactory.h',
+        'sound/soundsysteminterface.cc',
+        'sound/soundsysteminterface.h',
+        'sound/soundsystemproxy.cc',
+        'sound/soundsystemproxy.h',
+      ],
+      'conditions': [
+        ['OS=="linux"', {
+          'sources': [
+            'sound/alsasoundsystem.cc',
+            'sound/alsasoundsystem.h',
+            'sound/alsasymboltable.cc',
+            'sound/alsasymboltable.h',
+            'sound/linuxsoundsystem.cc',
+            'sound/linuxsoundsystem.h',
+            'sound/pulseaudiosoundsystem.cc',
+            'sound/pulseaudiosoundsystem.h',
+            'sound/pulseaudiosymboltable.cc',
+            'sound/pulseaudiosymboltable.h',
+          ],
+        }],
+      ],
+    },  # target libjingle_sound
+    {
       'target_name': 'libjingle_media',
       'type': 'static_library',
       'include_dirs': [
@@ -419,6 +461,7 @@
         '<(webrtc_root)/system_wrappers/source/system_wrappers.gyp:field_trial_default',
         '<(webrtc_root)/libjingle/xmllite/xmllite.gyp:rtc_xmllite',
         'libjingle',
+        'libjingle_sound',
       ],
       'direct_dependent_settings': {
         'include_dirs': [
diff --git a/talk/libjingle_tests.gyp b/talk/libjingle_tests.gyp
index 67d05b8..a44a950 100755
--- a/talk/libjingle_tests.gyp
+++ b/talk/libjingle_tests.gyp
@@ -104,6 +104,18 @@
       ],  # sources
     },  # target libjingle_unittest
     {
+      'target_name': 'libjingle_sound_unittest',
+      'type': 'executable',
+      'dependencies': [
+        '<(webrtc_root)/base/base_tests.gyp:rtc_base_tests_utils',
+        'libjingle.gyp:libjingle_sound',
+        'libjingle_unittest_main',
+      ],
+      'sources': [
+        'sound/automaticallychosensoundsystem_unittest.cc',
+      ],
+    },  # target libjingle_sound_unittest
+    {
       'target_name': 'libjingle_media_unittest',
       'type': 'executable',
       'dependencies': [
@@ -473,6 +485,20 @@
           ],
         },
         {
+          'target_name': 'libjingle_sound_unittest_run',
+          'type': 'none',
+          'dependencies': [
+            'libjingle_sound_unittest',
+          ],
+          'includes': [
+            'build/isolate.gypi',
+            'libjingle_sound_unittest.isolate',
+          ],
+          'sources': [
+            'libjingle_sound_unittest.isolate',
+          ],
+        },
+        {
           'target_name': 'libjingle_unittest_run',
           'type': 'none',
           'dependencies': [