Disable Poly1305 code only on bad chips.

base/cpu.h

Index: base/cpu.h
diff --git a/base/cpu.h b/base/cpu.h
index 595ed97b7ce2c1c2ddb1939d0ce47cd8b51eff65..0c809f00c8b98023a339242200114c9b2c28efd2 100644
--- a/base/cpu.h
+++ b/base/cpu.h
@@ -56,6 +56,11 @@ class BASE_EXPORT CPU {
   bool has_non_stop_time_stamp_counter() const {
     return has_non_stop_time_stamp_counter_;
   }
+  // has_broken_neon is only valid on ARM chips. If true, it indicates that we
+  // believe that the NEON unit on the current CPU is flawed and cannot execute
+  // some code. See https://code.google.com/p/chromium/issues/detail?id=341598
+  bool has_broken_neon() const { return has_broken_neon_; }
+
   IntelMicroArchitecture GetIntelMicroArchitecture() const;
   const std::string& cpu_brand() const { return cpu_brand_; }
 
@@ -81,6 +86,7 @@ class BASE_EXPORT CPU {
   bool has_avx_hardware_;
   bool has_aesni_;
   bool has_non_stop_time_stamp_counter_;
+  bool has_broken_neon_;
   std::string cpu_vendor_;
   std::string cpu_brand_;
 };