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| 1 // Copyright 2017 The Chromium Authors. All rights reserved. |
| 2 // Use of this source code is governed by a BSD-style license that can be |
| 3 // found in the LICENSE file. |
| 4 |
| 5 #include "content/renderer/previews_state_helper.h" |
| 6 |
| 7 #include <string> |
| 8 |
| 9 #include "base/macros.h" |
| 10 #include "base/strings/string_piece.h" |
| 11 #include "base/strings/string_split.h" |
| 12 #include "base/strings/string_util.h" |
| 13 #include "third_party/WebKit/public/platform/WebString.h" |
| 14 |
| 15 namespace content { |
| 16 |
| 17 namespace { |
| 18 |
| 19 // Chrome Proxy Previews header and directives. |
| 20 const char kChromeProxyHeader[] = "chrome-proxy"; |
| 21 const char kChromeProxyContentTransformHeader[] = |
| 22 "chrome-proxy-content-transform"; |
| 23 const char kChromeProxyPagePoliciesDirective[] = "page-policies"; |
| 24 const char kChromeProxyEmptyImageDirective[] = "empty-image"; |
| 25 const char kChromeProxyLitePageDirective[] = "lite-page"; |
| 26 |
| 27 bool HasEmptyImageDirective(const blink::WebURLResponse& web_url_response) { |
| 28 std::string chrome_proxy_value = |
| 29 web_url_response |
| 30 .HttpHeaderField(blink::WebString::FromUTF8(kChromeProxyHeader)) |
| 31 .Utf8(); |
| 32 for (const auto& directive : |
| 33 base::SplitStringPiece(chrome_proxy_value, ",", base::TRIM_WHITESPACE, |
| 34 base::SPLIT_WANT_NONEMPTY)) { |
| 35 if (!base::StartsWith(directive, kChromeProxyPagePoliciesDirective, |
| 36 base::CompareCase::INSENSITIVE_ASCII)) { |
| 37 continue; |
| 38 } |
| 39 |
| 40 // Check policy directive for empty-image entry. |
| 41 base::StringPiece page_policies_value = base::StringPiece(directive).substr( |
| 42 arraysize(kChromeProxyPagePoliciesDirective)); |
| 43 for (const auto& policy : |
| 44 base::SplitStringPiece(page_policies_value, "|", base::TRIM_WHITESPACE, |
| 45 base::SPLIT_WANT_NONEMPTY)) { |
| 46 if (base::LowerCaseEqualsASCII(policy, kChromeProxyEmptyImageDirective)) { |
| 47 return true; |
| 48 } |
| 49 } |
| 50 } |
| 51 return false; |
| 52 } |
| 53 |
| 54 } // namespace |
| 55 |
| 56 PreviewsState GetPreviewsStateFromMainFrameResponse( |
| 57 PreviewsState original_state, |
| 58 const blink::WebURLResponse& web_url_response) { |
| 59 if (original_state == PREVIEWS_UNSPECIFIED) { |
| 60 return PREVIEWS_OFF; |
| 61 } |
| 62 |
| 63 // Don't update the state if server previews were not enabled. |
| 64 if (!(original_state & SERVER_LITE_PAGE_ON)) { |
| 65 return original_state; |
| 66 } |
| 67 |
| 68 // At this point, this is a proxy main frame response for which the |
| 69 // PreviewsState needs to be updated from what was enabled/accepted by the |
| 70 // client to what the client should actually do based on the server response. |
| 71 |
| 72 PreviewsState updated_state = original_state; |
| 73 |
| 74 // Clear the Lite Page bit if Lite Page transformation did not occur. |
| 75 if (web_url_response |
| 76 .HttpHeaderField( |
| 77 blink::WebString::FromUTF8(kChromeProxyContentTransformHeader)) |
| 78 .Utf8() != kChromeProxyLitePageDirective) { |
| 79 updated_state &= ~(SERVER_LITE_PAGE_ON); |
| 80 } |
| 81 |
| 82 // Determine whether to keep or clear Lo-Fi bits. We need to receive the |
| 83 // empty-image policy directive and have SERVER_LOFI_ON in order to retain |
| 84 // Lo-Fi bits. |
| 85 if (!(original_state & SERVER_LOFI_ON)) { |
| 86 // Server Lo-Fi not enabled so ensure Client Lo-Fi off for this request. |
| 87 updated_state &= ~(CLIENT_LOFI_ON); |
| 88 } else if (!HasEmptyImageDirective(web_url_response)) { |
| 89 updated_state &= ~(SERVER_LOFI_ON | CLIENT_LOFI_ON); |
| 90 } |
| 91 |
| 92 // If we are left with no previews bits set, return the off state. |
| 93 if (updated_state == PREVIEWS_UNSPECIFIED) { |
| 94 return PREVIEWS_OFF; |
| 95 } |
| 96 |
| 97 return updated_state; |
| 98 } |
| 99 |
| 100 } // namespace content |
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