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 <agrieve@chromium.org>
Reviewed-by: Nico Weber <thakis@chromium.org>
Cr-Commit-Position: refs/heads/master@{#751101}

chrome/browser/BUILD.gn

@@ -5561,7 +5561,7 @@ grit("resources") {
   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
 

chrome/browser/resources/BUILD.gn

@@ -276,7 +276,7 @@ if (is_chromeos) {
     deps = [ "//chrome/browser/ui/webui/app_management:mojo_bindings_js" ]
     if (optimize_webui) {
       # Required due to flattenhtml="true" on a generated file.
-      source_is_generated = true
+      enable_input_discovery_for_gn_analyze = false
       source = "settings/os_settings_resources_vulcanized.grd"
 
       deps += [ "//chrome/browser/resources/settings/chromeos:build" ]

content/browser/devtools/BUILD.gn

@@ -14,7 +14,9 @@ group("resources") {
 
 grit("devtools_resources") {
   source = "$root_gen_dir/devtools/devtools_resources.grd"
-  source_is_generated = true
+
+  # Required because the .grd is generated.
+  enable_input_discovery_for_gn_analyze = false
   use_brotli = true
 
   outputs = [

content/browser/tracing/BUILD.gn

@@ -32,7 +32,9 @@ action("generate_tracing_grd") {
 
 grit("resources") {
   source = tracing_grd
-  source_is_generated = true
+
+  # Required because the .grd is generated.
+  enable_input_discovery_for_gn_analyze = false
 
   outputs = [
     "grit/tracing_resources.h",

ios/web/BUILD.gn

@@ -661,7 +661,7 @@ grit("resources") {
   source = "ios_web_resources.grd"
 
   # Required due to flattenhtml="true" on a generated file.
-  source_is_generated = true
+  enable_input_discovery_for_gn_analyze = false
 
   outputs = [
     "grit/ios_web_resources.h",

tools/grit/grit_rule.gni

@@ -14,13 +14,13 @@
 #   source (required)
 #       Path to .grd file.
 #
-#   source_is_generated (optional, defaults to false)
-#       Declares that the input (or one of its dependencies) is generated so
-#       that grit_info is not run on the file when
-#       compute_inputs_for_analyze is set (because the file will not
-#       exist at analyze time). For "analyze" to be correct in this case, the
-#       inputs to the grit file must either be listed in the inputs variable
-#       or are listed as inputs to dependencies of this target.
+#   enable_input_discovery_for_gn_analyze (default=true)
+#       Runs grit_info.py via exec_script() when compute_inputs_for_analyze=true
+#       in order to discover all files that affect this target.
+#       Turn this off when the .grd file is generated, or an <include> with
+#       flattenhtml=true points to a generated file.
+#       For "gn analyze" to be correct with this arg disabled, all inputs
+#       must be listed via |inputs|.
 #
 #   inputs  (optional)
 #       List of additional files, required for grit to process source file.
@@ -292,9 +292,10 @@ template("grit") {
     }
 
     _rebased_source_path = rebase_path(invoker.source, root_build_dir)
-    _source_is_generated =
-        defined(invoker.source_is_generated) && invoker.source_is_generated
-    if (!_source_is_generated && compute_inputs_for_analyze) {
+    _enable_grit_info =
+        !defined(invoker.enable_input_discovery_for_gn_analyze) ||
+        invoker.enable_input_discovery_for_gn_analyze
+    if (_enable_grit_info && compute_inputs_for_analyze) {
       # Only call exec_script when the user has explicitly opted into greater
       # precision at the expense of performance.
       _rel_inputs = exec_script("//tools/grit/grit_info.py",