Linux: use internal copy of libjpeg by default with mangled symbol names.

third_party/libjpeg/libjpeg.gyp

Index: third_party/libjpeg/libjpeg.gyp
diff --git a/third_party/libjpeg/libjpeg.gyp b/third_party/libjpeg/libjpeg.gyp
index 731a61cd2ea8905466d72ecfbf186b7299c6a17c..2e28b91dc077be96c2454956c7aca22a54c2b4ea 100644
--- a/third_party/libjpeg/libjpeg.gyp
+++ b/third_party/libjpeg/libjpeg.gyp
@@ -5,10 +5,11 @@
 {
   'variables': {
     'conditions': [
-      [ 'OS=="linux" or OS=="freebsd" or OS=="openbsd"', {
+      ['chromeos==1 or OS=="freebsd" or OS=="openbsd"', {
         # Link to system .so since we already use it due to GTK.
+        # See crbug.com/30288 and 31427 for why we skip OS=="linux" above.
         'use_system_libjpeg%': 1,
-      }, {  # OS!="linux" and OS!="freebsd" and OS!="openbsd"
+      }, {  # chromeos!=1 and OS!="freebsd" and OS!="openbsd"
         'use_system_libjpeg%': 0,
       }],
     ],