Refer to Chrome's DEPS to make rolling easier.

- Sync Chrome's DEPS to chromium_deps/, and use the From() keyword
  to pull the correct revisions from it, rather than having to manually
  enter them.
- This idea is borrowed from the WebKit DEPS:
http://trac.webkit.org/browser/trunk/Source/WebKit/chromium/DEPS
- Fix update.py's DEPS parsing to handle From().
- Roll Chrome 120526:122775.
- Organize the deps alphabetically.
- Sync the in-tree gold linker, which is now required due to a change
  in the linker flags.
- Add the new deps to .gitignore.

BUG=
TEST=build on all platforms

Review URL: https://webrtc-codereview.appspot.com/401004

git-svn-id: http://webrtc.googlecode.com/svn/trunk@1755 4adac7df-926f-26a2-2b94-8c16560cd09d

.gitignore

@@ -30,6 +30,7 @@
 .pydevproject
 .settings
 /build
+/chromium_deps
 /gyp-mac-tool
 /Makefile
 /out
@@ -40,6 +41,7 @@
 /third_party/cygwin
 /third_party/expat
 /third_party/gaeunit
+/third_party/gold
 /third_party/google-gflags/src
 /third_party/google-visualization-python
 /third_party/jsoncpp