Fix decoding of about:credits HTML (issue #1980)

BUILD.gn

@@ -614,6 +614,7 @@ static_library("libcef_static") {
     "//pdf",
     "//skia",
     "//storage/browser",
+    "//third_party/brotli",
     "//third_party/cld",
     "//third_party/hunspell",
     "//third_party/leveldatabase",

libcef/browser/net/chrome_scheme_handler.cc

@@ -281,6 +281,7 @@ class Delegate : public InternalHandlerDelegate {
     } else {
       action->mime_type = "text/html";
       action->resource_id = IDR_ABOUT_UI_CREDITS_HTML;
+      action->encoding = Action::ENCODING_BROTLI;
     }
     return true;
   }

libcef/browser/net/internal_scheme_handler.cc

@@ -14,6 +14,7 @@
 #include "base/strings/utf_string_conversions.h"
 #include "base/threading/thread_restrictions.h"
 #include "net/base/mime_util.h"
+#include "third_party/brotli/dec/decode.h"
 #include "ui/base/resource/resource_bundle.h"
 
 namespace scheme {
@@ -28,7 +29,7 @@ base::FilePath FilePathFromASCII(const std::string& str) {
 #endif
 }
 
-static std::string GetMimeType(const std::string& filename) {
+std::string GetMimeType(const std::string& filename) {
   // Requests should not block on the disk!  On POSIX this goes to disk.
   // http://code.google.com/p/chromium/issues/detail?id=59849
   base::ThreadRestrictions::ScopedAllowIO allow_io;
@@ -48,6 +49,24 @@ static std::string GetMimeType(const std::string& filename) {
   return "text/plain";
 }
 
+bool DecodeBrotli(const base::StringPiece& encoded,
+                  std::string& decoded) {
+  size_t decoded_size;
+
+  const uint8_t* encoded_response_buffer =
+      reinterpret_cast<const uint8_t*>(encoded.data());
+  if (!BrotliDecompressedSize(encoded.size(), encoded_response_buffer,
+                              &decoded_size)) {
+    return false;
+  }
+
+  decoded.resize(decoded_size);
+  return BrotliDecompressBuffer(encoded.size(), encoded_response_buffer,
+                               &decoded_size,
+                               reinterpret_cast<uint8_t*>(&decoded[0])) ==
+        BROTLI_RESULT_SUCCESS;
+}
+
 class RedirectHandler : public CefResourceHandler {
  public:
   explicit RedirectHandler(const GURL& url)
@@ -153,6 +172,16 @@ class InternalHandlerFactory : public CefSchemeHandlerFactory {
         base::StringPiece piece = CefContentClient::Get()->GetDataResource(
             action.resource_id, ui::SCALE_FACTOR_NONE);
         if (!piece.empty()) {
+          std::string decoded;
+          if (action.encoding ==
+                  InternalHandlerDelegate::Action::ENCODING_BROTLI &&
+              !DecodeBrotli(piece, decoded)) {
+            decoded = "Unable to decode content!";
+          }
+
+          if (!decoded.empty())
+            piece = base::StringPiece(decoded);
+
           action.stream =
               CefStreamReader::CreateForData(const_cast<char*>(piece.data()),
                                              piece.size());
@@ -183,7 +212,8 @@ class InternalHandlerFactory : public CefSchemeHandlerFactory {
 
 InternalHandlerDelegate::Action::Action()
     : stream_size(-1),
-      resource_id(-1) {
+      resource_id(-1),
+      encoding(ENCODING_NONE) {
 }
 
 CefRefPtr<CefSchemeHandlerFactory> CreateInternalHandlerFactory(

libcef/browser/net/internal_scheme_handler.h

@@ -28,8 +28,13 @@ class InternalHandlerDelegate {
     CefRefPtr<CefStreamReader> stream;
     int stream_size;
 
-    // Option 2: Specify a resource id to load static content.
+    // Option 2: Specify a resource id to load static content. May include an
+    // optional encoding type.
     int resource_id;
+    enum Encoding {
+      ENCODING_NONE,
+      ENCODING_BROTLI,
+    } encoding;
 
     // Option 3: Redirect to the specified URL.
     GURL redirect_url;