Take Murmur2 hash of untransformed icon when creating WebAPK part 1

chrome/browser/android/webapk/webapk_icon_hasher.cc

Index: chrome/browser/android/webapk/webapk_icon_hasher.cc
diff --git a/chrome/browser/android/webapk/webapk_icon_hasher.cc b/chrome/browser/android/webapk/webapk_icon_hasher.cc
new file mode 100644
index 0000000000000000000000000000000000000000..5c05a7e62c876da0553a8d9f39f7e5e812a19b0c
--- /dev/null
+++ b/chrome/browser/android/webapk/webapk_icon_hasher.cc
@@ -0,0 +1,53 @@
+// Copyright 2016 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/browser/android/webapk/webapk_icon_hasher.h"
+
+#include "base/strings/string_number_conversions.h"
+#include "base/strings/utf_string_conversions.h"
+#include "net/http/http_status_code.h"
+#include "net/url_request/url_fetcher.h"
+#include "net/url_request/url_request_context_getter.h"
+#include "third_party/smhasher/src/MurmurHash2.h"
+#include "url/gurl.h"
+
+namespace {
+
+// The seed to use when taking the murmur2 hash of the icon.
+const uint32_t kMurmur2HashSeed = 0;
+
+}  // anonymous namespace
+
+WebApkIconHasher::WebApkIconHasher() {}
+
+WebApkIconHasher::~WebApkIconHasher() {}
+
+void WebApkIconHasher::DownloadAndGetMurmur2Hash(
+    net::URLRequestContextGetter* request_context_getter,
+    const GURL& icon_url,
+    const Murmur2HashCallback& callback) {
+  callback_ = callback;
+
+  url_fetcher_ = net::URLFetcher::Create(icon_url, net::URLFetcher::GET, this);
+  url_fetcher_->SetRequestContext(request_context_getter);
+  url_fetcher_->Start();
+}
+
+void WebApkIconHasher::OnURLFetchComplete(const net::URLFetcher* source) {
+  if (!source->GetStatus().is_success() ||
+      source->GetResponseCode() != net::HTTP_OK) {
+    callback_.Run("");
+    return;
+  }
+
+  // WARNING: We are running in the browser process. |raw_image_data| is the
+  // image's raw, unsanitized bytes from the web. |raw_image_data| may contain
+  // malicious data. Decoding unsanitized bitmap data to an SkBitmap in the
+  // browser process is a security bug.
+  std::string raw_image_data;
+  source->GetResponseAsString(&raw_image_data);
+  uint64_t hash = MurmurHash64B(&raw_image_data.front(), raw_image_data.size(),
+                                kMurmur2HashSeed);
+  callback_.Run(base::Uint64ToString(hash));
+}