Rewrite YouTube Flash embeds

chrome/renderer/chrome_content_renderer_client.cc

 // Copyright (c) 2012 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 "chrome/renderer/chrome_content_renderer_client.h"
 
 #include <memory>
 #include <utility>
 
 #include "base/command_line.h"
 #include "base/debug/crash_logging.h"
 #include "base/logging.h"
 #include "base/macros.h"
 #include "base/metrics/field_trial.h"
 #include "base/metrics/histogram.h"
 #include "base/metrics/user_metrics_action.h"
 #include "base/strings/string_number_conversions.h"
 #include "base/strings/string_util.h"
 #include "base/strings/utf_string_conversions.h"
 #include "base/time/time.h"
 #include "base/values.h"
 #include "build/build_config.h"
 #include "chrome/common/channel_info.h"
 #include "chrome/common/chrome_isolated_world_ids.h"
+#include "chrome/common/chrome_features.h"
 #include "chrome/common/chrome_paths.h"
 #include "chrome/common/chrome_switches.h"
 #include "chrome/common/crash_keys.h"
 #include "chrome/common/pepper_permission_util.h"
 #include "chrome/common/render_messages.h"
 #include "chrome/common/secure_origin_whitelist.h"
 #include "chrome/common/url_constants.h"
 #include "chrome/grit/generated_resources.h"
 #include "chrome/grit/locale_settings.h"
 #include "chrome/grit/renderer_resources.h"
@@ skipping 1348 matching lines @@
 // chrome.system.network.getNetworkInterfaces provides the same
 // information. Also, the enforcement of sending and binding UDP is already done
 // by chrome extension permission model.
 bool ChromeContentRendererClient::ShouldEnforceWebRTCRoutingPreferences() {
 #if defined(ENABLE_EXTENSIONS)
   return !IsStandaloneExtensionProcess();
 #else
   return true;
 #endif
 }
+
+std::string ChromeContentRendererClient::OverrideFlashEmbedWithHTML(
+    const std::string& str_url) {
+  DCHECK(!str_url.empty());
+  GURL url = GURL(str_url);

[mlamouri (slow - plz ping), 2016/07/28 13:05:12]

You should move the `url` declaration after the FeatureList check.

[kdsilva, 2016/07/28 15:17:16]

Done.

+
+  // We'll only modify YouTube Flash embeds. The URLs can be recognized since
+  // they're in the following form: youtube.com/v/VIDEO_ID. So, we check to see
+  // if the given URL does follow that format. We don't modify
+  // any URLs that contain the enablejsapi=1 parameter since the page may be
+  // interacting with the YouTube Flash player in Javascript and we don't
+  // want to break working content.
+  //

[mlamouri (slow - plz ping), 2016/07/28 13:05:12]

style: remove this //

[kdsilva, 2016/07/28 15:17:16]

Done.

+  if (!base::FeatureList::IsEnabled(features::kOverrideFlashEmbed)) {
+    return "";
+  }

[mlamouri (slow - plz ping), 2016/07/28 13:05:12]

style: no { }

[kdsilva, 2016/07/28 15:17:16]

Done.

+
+  if (!url.DomainIs("youtube.com") || url.path().find("/v/") != 0
+      || str_url.find("enablejsapi=1") != std::string::npos)
+    return "";
+
+  std::string ret_url = str_url;
+  ret_url.replace(ret_url.find("/v/"), 3, "/embed/");
+
+  // If the website is using an invalid YouTube URL, we'll try and
+  // fix the URL by ensuring that IF there are multiple parameters,

[mlamouri (slow - plz ping), 2016/07/28 13:05:12]

s/IF/if/

[kdsilva, 2016/07/28 15:17:17]

Done.

+  // the parameter string begins with a "?" and then follows with a "&"
+  // for each subsequent parameter.
+  size_t index = ret_url.find_first_of("&?");
+  bool invalid_url = index != std::string::npos && ret_url.at(index) == '&';
+
+  if (!invalid_url)
+    return ret_url;
+
+  // Replace all instances of ? with &

[mlamouri (slow - plz ping), 2016/07/28 13:05:12]

Is this the fastest way to do what you want to do? We already have `index` that
points to the first &. It sounds like going back to `start_pos = 0` would waste
a few cycles.

What about an algorithm that does something like:
- set ret_url[index] to '?'
- find all '?' after `index` and replace them with '&'.

This should guarantee that we at max parse the string only once.

[kdsilva, 2016/07/28 15:17:16]

Done.

+  size_t start_pos = 0;
+  while ((start_pos = ret_url.find("?", start_pos)) != std::string::npos) {
+      ret_url.replace(start_pos, 1, "&");
+      start_pos += 1;
+  }
+
+  // ? should appear first before all parameters
+  ret_url.replace(index, 1, "?");
+  return ret_url;
+}