Fixes issues with upgrade_v8.

* The omahaproxy.appspot.com server is gone.
* The new dashboard only provides commit hashes.

deps/upgrade_v8.py

@@ -19,11 +19,11 @@
 package include
 
 import (
-	%s
+\t%s
 )
 """
 
-CHROME_VERSIONS_URL = "https://omahaproxy.appspot.com/all.json?os=linux&channel=stable"
+CHROME_VERSIONS_URL = "https://chromiumdash.appspot.com/fetch_releases?channel=Stable&platform=Linux&num=1&offset=0"
 V8_VERSION_FILE = "v8_version"
 
 deps_path = os.path.dirname(os.path.realpath(__file__))
@@ -55,7 +55,7 @@ def create_include_vendor_file(src_path, directories):
     package_names.append(package_name(directory_name, index, total_directories))
 
   with open(os.path.join(src_path, 'vendor.go'), 'w') as temp_file:
-      temp_file.write(include_vendor_file_template % ('  '.join(package_names)))
+      temp_file.write(include_vendor_file_template % ('\t'.join(package_names)))
 
 def create_vendor_files(src_path):
   directories = get_directories_names(src_path)
@@ -75,36 +75,37 @@ def create_vendor_files(src_path):
 
 def update_v8_version_file(src_path, version):
   with open(os.path.join(src_path, V8_VERSION_FILE), "w") as v8_file:
-    v8_file.write(version)
+    print(version, file=v8_file)
 
 def read_v8_version_file(src_path):
   v8_version_file = open(os.path.join(src_path, V8_VERSION_FILE), "r")
   return v8_version_file.read().strip()
 
-def get_latest_v8_info():
+def get_latest_v8_hash():
   with urllib.request.urlopen(CHROME_VERSIONS_URL) as response:
    json_response = response.read()
+   return json.loads(json_response)[0]["hashes"]["v8"]
 
-  return json.loads(json_response)
+def get_v8_version_tag():
+  tags = subprocess.check_output(["git", "tag", "--points-at", latest_stable_v8_hash], cwd=v8_path, env=env).decode('utf-8')
+  return tags.split(os.linesep)[0]
 
 # Current version
-current_v8_version_installed = read_v8_version_file(deps_path)
+current_v8_hash_installed = read_v8_version_file(deps_path)
 
 # Get latest version
-latest_v8_info = get_latest_v8_info()
+latest_stable_v8_hash = get_latest_v8_hash()
 
-latest_stable_v8_version = latest_v8_info[0]["versions"][0]["v8_version"]
-
-if current_v8_version_installed != latest_stable_v8_version:
-  subprocess.check_call(["git", "fetch", "origin", latest_stable_v8_version],
+if current_v8_hash_installed != latest_stable_v8_hash:
+  subprocess.check_call(["git", "fetch", "origin", latest_stable_v8_hash],
                         cwd=v8_path,
                         env=env)
-  # checkout latest stable commit
-  subprocess.check_call(["git", "checkout", latest_stable_v8_version],
+  latest_stable_v8_version = get_v8_version_tag()
+  subprocess.check_call(["git", "-c", "advice.detachedHead=false", "checkout", latest_stable_v8_version],
                         cwd=v8_path,
                         env=env)
 
   shutil.rmtree(deps_include_path)
   shutil.copytree(v8_include_path, deps_include_path, dirs_exist_ok=True)
   create_vendor_files(deps_include_path)
-  update_v8_version_file(deps_path, latest_stable_v8_version)
+  update_v8_version_file(deps_path, latest_stable_v8_hash)