Add content_unittests to chromium_builder_webrtc target.

We'd like to run parts of these tests for our Chromium buildbots.

TEST=none
BUG=none


Review URL: https://chromiumcodereview.appspot.com/13813009

git-svn-id: http://src.chromium.org/svn/trunk/src/build@193117 4ff67af0-8c30-449e-8e8b-ad334ec8d88c

all.gyp

@@ -409,6 +409,7 @@
             'chromium_builder_qa',  # needed for perf pyauto tests
             '../chrome/chrome.gyp:browser_tests',
             '../content/content.gyp:content_browsertests',
+            '../content/content.gyp:content_unittests',
             '../third_party/libjingle/libjingle.gyp:peerconnection_server',
             '../third_party/webrtc/tools/tools.gyp:frame_analyzer',
             '../third_party/webrtc/tools/tools.gyp:rgba_to_i420_converter',