Fix legacy script to pick up html prefix from external file

Change-Id: Id67f6a502b7688fb39ecdb70546eb3049111fdd2
diff --git a/systrace-legacy.py b/systrace-legacy.py
index 3ce7ce4..a20f6b5 100755
--- a/systrace-legacy.py
+++ b/systrace-legacy.py
@@ -176,6 +176,7 @@
             sys.stdout.write("downloading trace...")
             sys.stdout.flush()
             out = ''.join(lines[i+1:])
+            html_prefix = read_asset(script_dir, 'prefix.html')
             html_file = open(html_filename, 'w')
             html_file.write(html_prefix % (css, js, templates))
             trace_started = True
@@ -199,6 +200,7 @@
     html_out = dec.flush().replace('\n', '\\n\\\n').replace('\r', '')
     if len(html_out) > 0:
       html_file.write(html_out)
+    html_suffix = read_asset(script_dir, 'suffix.html')
     html_file.write(html_suffix)
     html_file.close()
     print " done\n\n    wrote file://%s\n" % (os.path.abspath(options.output_file))
@@ -206,6 +208,9 @@
     print >> sys.stderr, ('An error occured while capturing the trace.  Output ' +
       'file was not written.')
 
+def read_asset(src_dir, filename):
+  return open(os.path.join(src_dir, filename)).read()
+
 def get_assets(src_dir, build_dir):
   sys.path.append(build_dir)
   gen = __import__('generate_standalone_timeline_view', {}, {})
@@ -236,52 +241,6 @@
 
   return (js_files, js_flattenizer, css_files, templates)
 
-html_prefix = """<!DOCTYPE HTML>
-<html>
-<head i18n-values="dir:textdirection;">
-<title>Android System Trace</title>
-%s
-%s
-<script language="javascript">
-document.addEventListener('DOMContentLoaded', function() {
-  if (!linuxPerfData)
-    return;
-
-  var m = new tracing.TraceModel(linuxPerfData);
-  var timelineViewEl = document.querySelector('.view');
-  ui.decorate(timelineViewEl, tracing.TimelineView);
-  timelineViewEl.model = m;
-  timelineViewEl.tabIndex = 1;
-  timelineViewEl.timeline.focusElement = timelineViewEl;
-});
-</script>
-<style>
-  .view {
-    overflow: hidden;
-    position: absolute;
-    top: 0;
-    bottom: 0;
-    left: 0;
-    right: 0;
-  }
-</style>
-</head>
-<body>
-  <div>%s</div>
-  <div class="view">
-  </div>
-<!-- BEGIN TRACE -->
-  <script>
-  var linuxPerfData = "\\
-"""
-
-html_suffix = """\\n";
-  </script>
-<!-- END TRACE -->
-</body>
-</html>
-"""
-
 compiled_css_tag = """<style type="text/css">%s</style>"""
 compiled_js_tag = """<script language="javascript">%s</script>"""