[Smart Lock] Update Help Center URL.

BUG=419586
TEST=none
R=tengs@chromium.org

Review URL: https://codereview.chromium.org/697533002

Cr-Commit-Position: refs/heads/master@{#302517}

chrome/common/url_constants.cc

@@ -721,6 +721,6 @@ const char kMac32BitDeprecationURL[] =
 #endif
 
 const char kEasyUnlockLearnMoreUrl[] =
-    "https://support.google.com/chromebook/answer/6070209";
+    "https://support.google.com/chromebook/?p=easy_unlock";
 
 }  // namespace chrome