Update GN docs about Visual Studio generators

BUG=

Review URL: https://codereview.chromium.org/1750523002

Cr-Original-Commit-Position: refs/heads/master@{#378419}
Cr-Mirrored-From: https://chromium.googlesource.com/chromium/src
Cr-Mirrored-Commit: eca97f87e275a7c9c5b7f13a65ff8635f0821d46

tools/gn/docs/faq.md

diff --git a/tools/gn/docs/faq.md b/tools/gn/docs/faq.md
index cd32f6a..5a4bb07 100644
--- a/tools/gn/docs/faq.md
+++ b/tools/gn/docs/faq.md
@@ -31,19 +31,11 @@
 
 ## Will XCode/Visual Studio still be supported?
 
-They're not supported now.
+Visual Studio is supported. Visual Studio can be used as an IDE for code
+browsing or debugging but Ninja is used for building.
+Run `gn help gen` for more details.
 
-Long-term, if your use-case is to use Ninja for building but Visual
-Studio or XCode for debugging, there is desire to write a simple wrapper
-around Ninja that lists the files in Visual Studio or XCode format, and
-has a command to run ninja for when you press build. This setup should
-provide the type of interactive debugging experience people want (the
-iOS team currently uses a Ninja/XCode build like this with success).
-
-This project is not staffed. If you're interested, it probably isn't too
-hard. It won't get done unless somebody volunteers. There is a [spec for
-IDE
-integration](https://docs.google.com/document/d/1kwREU99u8GpRammLbbKwrfaDI6WV7nsMAaoF5dcuhOU/edit?usp=sharing).
+XCode is not supported yet. We need help!
 
 ## I'm weird. Will my uncommon build mode be supported?
 

tools/gn/docs/reference.md

diff --git a/tools/gn/docs/reference.md b/tools/gn/docs/reference.md
index 9ed3b87..40da46b 100644
--- a/tools/gn/docs/reference.md
+++ b/tools/gn/docs/reference.md
@@ -532,7 +532,7 @@
 ## **gn gen**: Generate ninja files.
 
 ```
-  gn gen [--ide=<ide_name>] <out_dir>
+  gn gen [<ide options>] <out_dir>
 
   Generates ninja files from the current tree and puts them in the given
   output directory.
@@ -542,12 +542,47 @@
   Or it can be a directory relative to the current directory such as:
       out/foo
 
-  --ide=<ide_name>
-    Also generate files for an IDE. Currently supported values:
-      'vs' - Visual Studio project/solution files.
-
   See "gn help switches" for the common command-line switches.
 
+```
+
+### **IDE options**
+
+```
+  GN optionally generates files for IDE. Possibilities for <ide options>
+
+  --ide=<ide_name>
+      Generate files for an IDE. Currently supported values:
+      "eclipse" - Eclipse CDT settings file.
+      "vs" - Visual Studio project/solution files.
+             (default Visual Studio version: 2015)
+      "vs2013" - Visual Studio 2013 project/solution files.
+      "vs2015" - Visual Studio 2015 project/solution files.
+
+  --sln=<file_name>
+      Override default sln file name ("all"). Solution file is written
+      to the root build directory. Only for Visual Studio.
+
+  --filters=<path_prefixes>
+      Semicolon-separated list of label patterns used to limit the set
+      of generated projects (see "gn help label_pattern"). Only
+      matching targets will be included to the solution. Only for Visual
+      Studio.
+
+```
+
+### **Eclipse IDE Support**
+
+```
+  GN DOES NOT generate Eclipse CDT projects. Instead, it generates a
+  settings file which can be imported into an Eclipse CDT project. The
+  XML file contains a list of include paths and defines. Because GN does
+  not generate a full .cproject definition, it is not possible to
+  properly define includes/defines for each file individually.
+  Instead, one set of includes/defines is generated for the entire
+  project. This works fairly well but may still result in a few indexer
+  issues here and there.
+
 
 ```
 ## **gn help <anything>**