Update Linux eclipse docs for GN

Review-Url: https://codereview.chromium.org/2122603005
Cr-Commit-Position: refs/heads/master@{#415820}

docs/linux_eclipse_dev.md

@@ -287,20 +287,13 @@ requires the Eclipse knows correct include paths and pre-processor definitions.
 After fighting with with a number of approaches, I've found the below to work
 best for me.
 
-*The instrcutions below are out-of-date since it references GYP. Please see
-`gn help gen` for how to generate an Eclipse CDT file in GN. If you use
-Eclipse and make it work, please update this documentation.*
-
 1.  From a shell in your src directory, run
-    `GYP_GENERATORS=ninja,eclipse build/gyp_chromium`
-    1.  This generates <project root>/out/Debug/eclipse-cdt-settings.xml which
+    `gn gen --ide=eclipse out/Debug_gn/' (replacing Debug_gn with the output directory you normally use when building).
+    1.  This generates <project root>/out/Debug_gn/eclipse-cdt-settings.xml which
         is used below.
     1.  This creates a single list of include directories and preprocessor
         definitions to be used for all source files, and so is a little
         inaccurate. Here are some tips for compensating for the limitations:
-        1.  Use `-R <target>` to restrict the output to considering only certain
-            targets (avoiding unnecessary includes that are likely to cause
-            trouble). Eg. for a blink project, use `-R blink`.
         1.  If you care about blink, move 'third\_party/Webkit/Source' to the
             top of the list to better resolve ambiguous include paths (eg.
             `config.h`).