Don't propagate deps across actions in GN.

tools/gn/variables.cc

Index: tools/gn/variables.cc
diff --git a/tools/gn/variables.cc b/tools/gn/variables.cc
index aa4de3650fa2cd621b0963a873191c2162e12c05..7898273fee24085d7085fb9033d551e2df2cec9c 100644
--- a/tools/gn/variables.cc
+++ b/tools/gn/variables.cc
@@ -722,14 +722,31 @@ const char kDeps_Help[] =
     "\n"
     "  A list of target labels.\n"
     "\n"
-    "  Specifies private dependencies of a target. Shared and dynamic\n"
-    "  libraries will be linked into the current target.\n"
+    "  Specifies private dependencies of a target. Private dependencies are\n"
+    "  propagated up the dependency tree and linked to dependant targets, but\n"
+    "  do not grant the ability to include headers from the dependency.\n"
+    "  Public configs are not forwarded.\n"
     "\n"
-    "  These dependencies are private in that it does not grant dependent\n"
-    "  targets the ability to include headers from the dependency, and direct\n"
-    "  dependent configs are not forwarded.\n"
+    "Details of dependency propagation\n"
     "\n"
-    "  See also \"public_deps\" and \"data_deps\".\n";
+    "  Source sets, shared libraries, and non-complete static libraries\n"
+    "  will be propagated up the dependency tree across groups, non-complete\n"
+    "  static libraries and source sets.\n"
+    "\n"
+    "  Executables, shared libraries, and complete static libraries will\n"
+    "  link all propagated targets and stop propagation. Actions and copy\n"
+    "  steps also stop propagation, allowing them to take a library as an\n"
+    "  input but not force dependants to link to it.\n"
+    "\n"
+    "  Propagation of all_dependent_configs and public_configs happens\n"
+    "  independently of target type. all_dependent_configs are always\n"
+    "  propagated across all types of targets, and public_configs\n"
+    "  are always propagated across public deps of all types of targets.\n"
+    "\n"
+    "  Data dependencies are propagated differently. See\n"
+    "  \"gn help data_deps\" and \"gn help runtime_deps\".\n"
+    "\n"
+    "  See also \"public_deps\".\n";
 
 const char kIncludeDirs[] = "include_dirs";
 const char kIncludeDirs_HelpShort[] =
@@ -1122,9 +1139,9 @@ const char kPublicDeps_HelpShort[] =
 const char kPublicDeps_Help[] =
     "public_deps: Declare public dependencies.\n"
     "\n"
-    "  Public dependencies are like private dependencies (\"deps\") but\n"
-    "  additionally express that the current target exposes the listed deps\n"
-    "  as part of its public API.\n"
+    "  Public dependencies are like private dependencies (see\n"
+    "  \"gn help deps\") but additionally express that the current target\n"
+    "  exposes the listed deps as part of its public API.\n"
     "\n"
     "  This has several ramifications:\n"
     "\n"