Add --ignore-certificate-errors-spki-list switch and UMA histogram.

content/public/common/content_switches.cc

Index: content/public/common/content_switches.cc
diff --git a/content/public/common/content_switches.cc b/content/public/common/content_switches.cc
index 313f2fae584c13f37ed5ed5010bfed47debc5832..7fdda4e6bc3585a8f9059a334dbe71c27e9aa3b7 100644
--- a/content/public/common/content_switches.cc
+++ b/content/public/common/content_switches.cc
@@ -583,6 +583,16 @@ const char kGpuStartupDialog[]              = "gpu-startup-dialog";
 // Ignores certificate-related errors.
 const char kIgnoreCertificateErrors[]       = "ignore-certificate-errors";
 
+// A set of public key hashes for which to ignore certificate-related errors.
+// If the certificate chain presented by the server does not validate, and one
+// or more certificates have public key hashes that match a key from this list,
+// the error is ignored.
+//
+// The switch value must a be a comma-separated list of Base64-encoded SHA-256
+// SPKI Fingerprints (RFC 7469, Section 2.4).
+const char kIgnoreCertificateErrorsSPKIList[] =
+    "ignore-certificate-errors-spki-list";
+
 // Don't allow content to arbitrarily append to the back/forward list.
 // The page must prcoess a user gesture before an entry can be added.
 const char kHistoryEntryRequiresUserGesture[] =