Use <(webrtc_root) to point to webrtc files in tools.gyp.

TBR=brykt@google.com

Review URL: https://webrtc-codereview.appspot.com/939034

git-svn-id: http://webrtc.googlecode.com/svn/trunk/webrtc@3206 4adac7df-926f-26a2-2b94-8c16560cd09d
diff --git a/tools/tools.gyp b/tools/tools.gyp
index 8c2d100..fd5f46d 100644
--- a/tools/tools.gyp
+++ b/tools/tools.gyp
@@ -88,7 +88,7 @@
       'target_name': 'frame_cutter_lib',
       'type': '<(library)',
       'dependencies': [
-        '<(DEPTH)/webrtc/common_video/common_video.gyp:common_video',
+        '<(webrtc_root)/common_video/common_video.gyp:common_video',
       ],
       'sources': [
         'frame_cutter/frame_cutter_lib.cc',