Refactor OriginTrialPolicy to be an abstract interface in content/public/common

chrome/common/origin_trials/chrome_origin_trial_policy.cc

+// Copyright 2016 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "chrome/common/origin_trials/chrome_origin_trial_policy.h"
+
+#include <stdint.h>
+
+#include "base/base64.h"
+#include "base/command_line.h"
+#include "chrome/common/chrome_switches.h"
+
+// This is the default public key used for validating signatures.
+// TODO(iclelland): Provide a mechanism to allow for multiple signing keys.
+// https://crbug.com/584737
+static const uint8_t kDefaultPublicKey[] = {
+    0x7c, 0xc4, 0xb8, 0x9a, 0x93, 0xba, 0x6e, 0xe2, 0xd0, 0xfd, 0x03,
+    0x1d, 0xfb, 0x32, 0x66, 0xc7, 0x3b, 0x72, 0xfd, 0x54, 0x3a, 0x07,
+    0x51, 0x14, 0x66, 0xaa, 0x02, 0x53, 0x4e, 0x33, 0xa1, 0x15,
+};
+
+ChromeOriginTrialPolicy::ChromeOriginTrialPolicy()
+    : public_key_(std::string(reinterpret_cast<const char*>(kDefaultPublicKey),
+                              arraysize(kDefaultPublicKey))) {
+  // Set the public key for the origin trial key manager, based on the command
+  // line flags which were passed to this process. If the flag is not present,
+  // or is incorrectly formatted, the default key will remain active.
+  if (base::CommandLine::InitializedForCurrentProcess()) {
+    base::CommandLine* command_line = base::CommandLine::ForCurrentProcess();
+    if (command_line->HasSwitch(switches::kOriginTrialPublicKey)) {
+      SetPublicKeyFromASCIIString(
+        command_line->GetSwitchValueASCII(switches::kOriginTrialPublicKey));
+    }
+  }
+}
+
+ChromeOriginTrialPolicy::~ChromeOriginTrialPolicy() {}
+
+base::StringPiece ChromeOriginTrialPolicy::GetPublicKey() const {
+  return base::StringPiece(public_key_);
+}
+
+bool ChromeOriginTrialPolicy::SetPublicKeyFromASCIIString(
+    const std::string& ascii_public_key) {
+  // Base64-decode the incoming string. Set the key if it is correctly formatted
+  std::string new_public_key;
+  if (!base::Base64Decode(ascii_public_key, &new_public_key))
+    return false;
+  if (new_public_key.size() != 32)
+    return false;
+  public_key_.swap(new_public_key);
+  return true;
+}