[memory-inspector] Fix zygote wrapper script and UI scrolling

This is a minor fix to the Zygote wrapper script (for full profiles).
Furthermore, this adds a workaround to a recent regression of the
Google Data Table UI (https://goo.gl/TXr3vL) which was causing the
Memory Inspector UI to forget its scroll position every couple of
seconds.

BUG=

Review URL: https://codereview.chromium.org/1138523003

Cr-Commit-Position: refs/heads/master@{#329666}

tools/memory_inspector/memory_inspector/backends/android_backend.py

@@ -234,7 +234,7 @@ class AndroidDevice(backends.Device):
         wrapper_file.write('#!/system/bin/sh\n'
                            'LD_PRELOAD="libheap_profiler.so:$LD_PRELOAD" '
                            'exec %s.real "$@"\n' % app_process)
-        wrapper_file.close()
+        wrapper_file.flush()
         self.adb.Push(wrapper_file.name, app_process)
       self.adb.Shell(['chown', 'root.shell', app_process])
       self.adb.Shell(['chmod', '755', app_process])

tools/memory_inspector/memory_inspector/frontends/www_content/js/processes.js

@@ -46,6 +46,8 @@ this.onDomReady_ = function() {
   this.psTable_ = new google.visualization.Table($('#ps-table')[0]);
   google.visualization.events.addListener(
       this.psTable_, 'select', this.onPsTableRowSelect_.bind(this));
+  google.visualization.events.addListener(
+      this.psTable_, 'ready', this.onPsTableRedrawn_.bind(this));
   $('#ps-table').on('dblclick', this.snapshotSelectedProcess_.bind(this));
 
   // Create the device stats charts.
@@ -199,6 +201,10 @@ this.onPsTableRowSelect_ = function() {
   this.startSelectedProcessStats();
 };
 
+this.onPsTableRedrawn_ = function() {
+  rootUi.restoreScrollPosition();
+};
+
 this.onPsAjaxResponse_ = function(data) {
   this.psTableData_ = new google.visualization.DataTable(data);
   this.redrawPsTable_();
@@ -210,6 +216,7 @@ this.redrawPsTable_ = function(data) {
 
   // Redraw table preserving sorting info.
   var sort = this.psTable_.getSortInfo() || {column: -1, ascending: false};
+  rootUi.saveScrollPosition();
   this.psTable_.draw(this.psTableData_, {sortColumn: sort.column,
                                          sortAscending: sort.ascending});
 };

tools/memory_inspector/memory_inspector/frontends/www_content/js/rootUi.js

@@ -4,6 +4,8 @@
 
 rootUi = new (function() {
 
+this.savedScrollTop_ = 0;
+
 this.onDomReady_ = function() {
   $('#js_loading_banner').hide();
   $('#tabs').tabs({activate: this.onTabChange_.bind(this)});
@@ -84,6 +86,15 @@ this.onServerUnreachableOrTimeout = function() {
                   'It probably crashed, Check the terminal output.');
 };
 
+// Sad hack required to work around a Google Table bug (goo.gl/TXr3vL).
+this.saveScrollPosition = function() {
+  this.savedScrollTop_ = $('#wrapper').scrollTop();
+};
+
+this.restoreScrollPosition = function() {
+  $('#wrapper').scrollTop(this.savedScrollTop_);
+};
+
 $(document).ready(this.onDomReady_.bind(this));
 
 })();