Factor DRP PreviewsState logic out of content

content/renderer/previews_state_helper.cc

Index: content/renderer/previews_state_helper.cc
diff --git a/content/renderer/previews_state_helper.cc b/content/renderer/previews_state_helper.cc
deleted file mode 100644
index 4528f370136c9731d3f63061efc6aa8f2efb8c9a..0000000000000000000000000000000000000000
--- a/content/renderer/previews_state_helper.cc
+++ /dev/null
@@ -1,100 +0,0 @@
-// Copyright 2017 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 "content/renderer/previews_state_helper.h"
-
-#include <string>
-
-#include "base/macros.h"
-#include "base/strings/string_piece.h"
-#include "base/strings/string_split.h"
-#include "base/strings/string_util.h"
-#include "third_party/WebKit/public/platform/WebString.h"
-
-namespace content {
-
-namespace {
-
-// Chrome Proxy Previews header and directives.
-const char kChromeProxyHeader[] = "chrome-proxy";
-const char kChromeProxyContentTransformHeader[] =
-    "chrome-proxy-content-transform";
-const char kChromeProxyPagePoliciesDirective[] = "page-policies";
-const char kChromeProxyEmptyImageDirective[] = "empty-image";
-const char kChromeProxyLitePageDirective[] = "lite-page";
-
-bool HasEmptyImageDirective(const blink::WebURLResponse& web_url_response) {
-  std::string chrome_proxy_value =
-      web_url_response
-          .HttpHeaderField(blink::WebString::FromUTF8(kChromeProxyHeader))
-          .Utf8();
-  for (const auto& directive :
-       base::SplitStringPiece(chrome_proxy_value, ",", base::TRIM_WHITESPACE,
-                              base::SPLIT_WANT_NONEMPTY)) {
-    if (!base::StartsWith(directive, kChromeProxyPagePoliciesDirective,
-                          base::CompareCase::INSENSITIVE_ASCII)) {
-      continue;
-    }
-
-    // Check policy directive for empty-image entry.
-    base::StringPiece page_policies_value = base::StringPiece(directive).substr(
-        arraysize(kChromeProxyPagePoliciesDirective));
-    for (const auto& policy :
-         base::SplitStringPiece(page_policies_value, "|", base::TRIM_WHITESPACE,
-                                base::SPLIT_WANT_NONEMPTY)) {
-      if (base::LowerCaseEqualsASCII(policy, kChromeProxyEmptyImageDirective)) {
-        return true;
-      }
-    }
-  }
-  return false;
-}
-
-}  // namespace
-
-PreviewsState GetPreviewsStateFromMainFrameResponse(
-    PreviewsState original_state,
-    const blink::WebURLResponse& web_url_response) {
-  if (original_state == PREVIEWS_UNSPECIFIED) {
-    return PREVIEWS_OFF;
-  }
-
-  // Don't update the state if server previews were not enabled.
-  if (!(original_state & SERVER_LITE_PAGE_ON)) {
-    return original_state;
-  }
-
-  // At this point, this is a proxy main frame response for which the
-  // PreviewsState needs to be updated from what was enabled/accepted by the
-  // client to what the client should actually do based on the server response.
-
-  PreviewsState updated_state = original_state;
-
-  // Clear the Lite Page bit if Lite Page transformation did not occur.
-  if (web_url_response
-          .HttpHeaderField(
-              blink::WebString::FromUTF8(kChromeProxyContentTransformHeader))
-          .Utf8() != kChromeProxyLitePageDirective) {
-    updated_state &= ~(SERVER_LITE_PAGE_ON);
-  }
-
-  // Determine whether to keep or clear Lo-Fi bits. We need to receive the
-  // empty-image policy directive and have SERVER_LOFI_ON in order to retain
-  // Lo-Fi bits.
-  if (!(original_state & SERVER_LOFI_ON)) {
-    // Server Lo-Fi not enabled so ensure Client Lo-Fi off for this request.
-    updated_state &= ~(CLIENT_LOFI_ON);
-  } else if (!HasEmptyImageDirective(web_url_response)) {
-    updated_state &= ~(SERVER_LOFI_ON | CLIENT_LOFI_ON);
-  }
-
-  // If we are left with no previews bits set, return the off state.
-  if (updated_state == PREVIEWS_UNSPECIFIED) {
-    return PREVIEWS_OFF;
-  }
-
-  return updated_state;
-}
-
-}  // namespace content