M38 gardening: AppCacheService is in content now.

CL: https://codereview.chromium.org/344493002
M38 gardening: Update HandleExternalProtocol's signature.

CL: https://codereview.chromium.org/426713002
M38 gardening: adapt to ResourceType's changes.

CL: https://codereview.chromium.org/425653002
M38 gardening: ServerBoundCert is now ChannelID.

CL: https://codereview.chromium.org/356713005
M38 gardening: Remove reference to switches::kEnableGestureTapHighlight.

It is now always enabled unconditionally.

CL: https://codereview.chromium.org/393653002
M38 gardening: conditionally include nacl_process_host.h.

CL: https://codereview.chromium.org/421613002
M38 gardening: Changes to WebNotification-related signatures.

CL: https://codereview.chromium.org/405633002
M38 gardening: drop NaCl dependencies when it is disabled.

CL: https://codereview.chromium.org/321423002
M38 gardening: Add missing method to RuntimeContext.

CL: https://codereview.chromium.org/369703002
M38 gardening: Stop including platformfile.h.

CL: https://codereview.chromium.org/326383005
M38 gardening: Move jni_helper.h include location.

CL: https://codereview.chromium.org/336313018
M38 gardening: webpreferences.h has moved.

CL: https://codereview.chromium.org/357203003
M38 gardening: unix_domain_socket_posix.h has been renamed.

CL: https://codereview.chromium.org/376323002
M38 gardening: Use WebLocalFrame in DidCommitProvisionalLoad.

CL: https://codereview.chromium.org/222973003
M38 gardening: Adjust allowImage's signature.

CL: https://codereview.chromium.org/225303007
M38 gardening: getElementsByTagName() is deprecated.

CL: https://codereview.chromium.org/403673002