Suppress -Wswitch for pdfium's fxge target for now.

BUILD.gn

Index: BUILD.gn
diff --git a/BUILD.gn b/BUILD.gn
index 22265b12cb1eb8916c0261b3d6808092fc043009..3cc46180a6a5f0d96078179cf261a06f795d0fd0 100644
--- a/BUILD.gn
+++ b/BUILD.gn
@@ -505,10 +505,19 @@ static_library("fxge") {
     "core/src/fxge/ge/text_int.h",
   ]
 
+  config("fxge_warnings") {
+    if (is_clang) {
+      cflags = [
+        # http://code.google.com/p/pdfium/issues/detail?id=188
+        "-Wno-switch",
+      ]
+    }
+  }
   configs -= [ "//build/config/compiler:chromium_code" ]
   configs += [
     ":pdfium_config",
     "//build/config/compiler:no_chromium_code",
+    ":fxge_warnings",
   ]
 
   if (pdf_use_skia) {