Remove most things GYP.

DEPS

Index: DEPS
diff --git a/DEPS b/DEPS
index 7e32009166594443649b7f26af03bae2b23f01cc..d168db760ae76cf8580860368480f97a3410fd38 100644
--- a/DEPS
+++ b/DEPS
@@ -50,6 +50,7 @@ deps = {
     Var('chromium_git') + "/chromium/src/tools/generate_library_loader@" +
         Var('gen_library_loader_revision'),
 
+  # TODO(GYP): Remove this when no tools rely on GYP anymore.
   "tools/gyp":
     Var('chromium_git') + '/external/gyp.git' + '@' + 'c61b0b35c8396bfd59efc6cfc11401d912b0f510',
 
@@ -138,12 +139,6 @@ hooks = [
                '--running-as-hook'
     ],
   },
-  {
-    # A change to a .gyp, .gypi, or to GYP itself should run the generator.
-    'name': 'gyp',
-    'pattern': '.',
-    'action': ['python', 'pdfium/build_gyp/gyp_pdfium'],
-  },
   # Pull clang-format binaries using checked-in hashes.
   {
     'name': 'clang_format_win',