Rename source_is_generated -> enable_input_discovery_for_gn_analyze

And update docs for the setting.

TBR=agrieve  # Mechanical rename

Bug: 1054892
Change-Id: I7303eb44046f70fae7e6c6a11c7aacc913ef8654
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2107413
Commit-Queue: Andrew Grieve <[email protected]>
Reviewed-by: Nico Weber <[email protected]>
Cr-Commit-Position: refs/heads/master@{#751101}
diff --git a/chrome/browser/BUILD.gn b/chrome/browser/BUILD.gn
index e608e3a9..0d8c838 100644
--- a/chrome/browser/BUILD.gn
+++ b/chrome/browser/BUILD.gn
@@ -5561,7 +5561,7 @@
   source = "browser_resources.grd"
 
   # Required due to flattenhtml="true" on a generated file.
-  source_is_generated = true
+  enable_input_discovery_for_gn_analyze = false
 
   use_brotli = true