Update tools/gn/README.md.

tools/gn/README.md

 # What is GN?
 
 GN is a meta-build system that generates
-[NinjaBuild](https://chromium.googlesource.com/chromium/src/+/master/docs/ninja_build.md)
+[NinjaBuild](/chromium/src/+/master/docs/ninja_build.md)
 files. It's meant to be faster and simpler than GYP. It outputs only Ninja build
 files.
 
 ## Why bother with GN?
 
 1. We believe GN files are more readable and more maintainable
    than GYP files.
 2. GN is fast:
-  * GN is 20x faster than GYP (as of mid November, building 80%
-    of what GYP builds, in one configuration rather than two, takes 500ms
-    on a z620 running Ubuntu Trusty. GYP takes 20 seconds.
-    We see similar speedups on Mac and Windows).
+  * GN is 20x faster than GYP.
   * GN supports automatically re-running itself as needed by Ninja
     as part of the build. This eliminates the need to remember to
     re-run GN when you change a build file.
 3. GN gives us better tools for enforcing dependencies (see
    `gn check` and the `visibility`, `public_deps`, and `data_deps`
    options for some examples).
 4. GN gives us tools for querying the build graph; you can ask
    "what does X depend on" and "who depends on Y", for example.
 
 ## What's the status?
 
-_as of 8 Feb 2015:_
+_as of 7 Oct 2015:_
 
-Chrome and most of the major test suites link on Linux and ChromeOS.
-There's probably <1000 objects left to build, in a few test suites and a
-bunch of utillities and helper binaries. We will probably have
-everything converted in another couple weeks.
+GN is now the default system for Linux, though GYP still works. It
+is mostly complete on Android, ChromeOS, and Windows (apart from NaCl
+support on Windows).
 
-Chrome also links on Android and Windows, and bringing up the remaining
-test suites should be mostly straightforward. There's some work left to
-enable NaCl on Windows but it should also be straightforward.
-
-Mac and iOS have not progressed much as attention has been focused on
-Linux and Windows; we still need support for bundles and frameworks
-before it can get to parity w/ the other platforms.
+Mac and iOS are making progress, though we still need better support
+for bundles before the major targets like Chrome can link and they get
+to parity w/ the other platforms.
 
 ## When are you going to be done?
 
-_as of 8 Feb 2015:_
+_as of 7 Oct 2015:_
 
-We're currently shooting for having the main developer configurations
-working and usable by the end of March 2015. There will probably be a
-fair amount of verification of flags, bug fixes, etc over the next
-couple months, but hopefully we will be flipping configurations from GYP
-to GN throughout Q2, targeting having everything done by the end of Q2.
+We're currently shooting for having Android, ChromeOS, and Windows
+converted over by the end of 2015, with Mac and iOS following in Q1
+of 2016.
 
 ## What does "done" mean?
 
 Ideally we're done when all of the GYP files have been deleted from
 Chromium and no one misses them.
 
 We will be "mostly" done when the following are true:
 
   * All of the bots maintained by the Chrome infra team for Chromium and
     downstream of Chromium have been switched to GN. (Upstream projects
@@ skipping 16 matching lines @@
 
 We do not currently plan to support full native XCode or Visual Studio
 generation from GN. It is theoretically possible to support such things,
 so we would at least look at patches adding the functionality.
 
 ## How can I help?
 
 Check to see if your targets build under GN yet. If they don't,
 volunteer to help convert them!
 
-_17 Nov 2014. We are updating the stuff we use to track progress. Watch
-this space and chromium-dev@ for more info!_.
+Or, look at [the list of open bugs](https://code.google.com/p/chromium/issues/list?can=2&q=label:Proj-GN-Migration%20-type:Project&sort=pri&colspec=ID%20Pri%20Summary%20Type%20OS%20Owner%20Status%20Modified%20Blocking) related to the migration and see if there's anything that catches your fancy.
 
 ## I want more info on GN!
 
 Read these links:
 
-  * [Quick start](docs/quick_start.md)
-  * [FAQ](docs/faq.md)
-  * [GYP conversion cookbook](docs/cookbook.md)
-  * [Language and operation details](docs/language.md)
-  * [Reference](docs/reference.md) The built-in `gn help` documentation.
-  * [Style guide](docs/style_guide.md)
-  * [Cross compiling and toolchains](docs/cross_compiles.md)
-  * [Hacking on GN itself](docs/hacking.md)
-  * [GNStandalone](docs/standalone.md) Standalone GN projects
-  * [UpdateGNBinaries](docs/update_binaries.md) Pushing new binaries
-  * [Check](docs/check.md) `gn check` command reference
+  * [Quick start](/chromium/src/+/master/tools/gn/docs/quick_start.md)
+  * [FAQ](/chromium/src/+/master/tools/gn/docs/faq.md)
+  * [GYP conversion cookbook](/chromium/src/+/master/tools/gn/docs/cookbook.md)
+  * [Language and operation details](/chromium/src/+/master/tools/gn/docs/language.md)
+  * [Reference](/chromium/src/+/master/tools/gn/docs/reference.md) The built-in `gn help` documentation.
+  * [Style guide](/chromium/src/+/master/tools/gn/docs/style_guide.md)
+  * [Cross compiling and toolchains](/chromium/src/+/master/tools/gn/docs/cross_compiles.md)
+  * [Hacking on GN itself](/chromium/src/+/master/tools/gn/docs/hacking.md)
+  * [GNStandalone](/chromium/src/+/master/tools/gn/docs/standalone.md) Standalone GN projects
+  * [UpdateGNBinaries](/chromium/src/+/master/tools/gn/docs/update_binaries.md) Pushing new binaries
+  * [Check](/chromium/src/+/master/tools/gn/docs/check.md) `gn check` command reference