Properly set loopback device ID for system audio capture.

chrome/chrome_browser.gypi

Index: chrome/chrome_browser.gypi
diff --git a/chrome/chrome_browser.gypi b/chrome/chrome_browser.gypi
index df4f7ae9fde2dbc26239227e81aa893356175ad5..3ff6c588421665f566f05361fca5656ab16c0888 100644
--- a/chrome/chrome_browser.gypi
+++ b/chrome/chrome_browser.gypi
@@ -7,7 +7,10 @@
     {
       'target_name': 'browser',
       'type': 'static_library',
-      'variables': { 'enable_wexit_time_destructors': 1, },
+      'variables': {
+        'enable_wexit_time_destructors': 1,
+        'use_cras%': 0,

[DaleCurtis, 2013/08/07 18:43:11]

Should this be in build/common.gypi instead?

[hshi1, 2013/08/07 18:50:24]

Great suggestion! Yes I agree this should just go to common.gypi and we won't
have to worry about individual gypi's. Done.

+      },
       'dependencies': [
         # NOTE: New dependencies should generally be added in the OS!="ios"
         # dependencies block below, rather than here.
@@ -2829,6 +2832,11 @@
             }],
           ],
         }],
+        ['use_cras==1', {
+          'defines': [
+            'USE_CRAS',
+          ],
+        }],
         ['ui_compositor_image_transport==1', {
           'dependencies': [
             '../ui/gl/gl.gyp:gl',