Add back buttons and load new 'pages' by calling javascript.

build/android/pylib/results/presentation/javascript/main_html.js

Index: build/android/pylib/results/presentation/javascript/main_html.js
diff --git a/build/android/pylib/results/presentation/javascript/main_html.js b/build/android/pylib/results/presentation/javascript/main_html.js
index 6c254d5a6885ffdae66f9422161f0a9ebc031954..7a6158ac6b7176a0dec42ceb3761bf07f500c654 100644
--- a/build/android/pylib/results/presentation/javascript/main_html.js
+++ b/build/android/pylib/results/presentation/javascript/main_html.js
@@ -26,7 +26,7 @@ function showTestTable(show_the_table) {
         show_the_table ? 'table' : 'none');
 }
 
-function showTestsOfOneSuiteOnly(suite_name) {
+function showTestsOfOneSuiteOnly(suite_name, push_state) {
   setTitle('Test Results of Suite: ' + suite_name)
   show_all = (suite_name == 'TOTAL')
   var testTableBlocks = document.getElementById('test-table')
@@ -46,12 +46,30 @@ function showTestsOfOneSuiteOnly(suite_name) {
       });
   showTestTable(true);
   showSuiteTable(false);
+  window.scrollTo(0, 0);

[jbudorick, 2017/04/11 17:52:47]

Why are we now scrolling to the top?

[BigBossZhiling, 2017/04/11 18:37:51]

Acknowledged.

+  if (push_state) {

[jbudorick, 2017/04/11 17:52:47]

Should this & replace_state be in these two functions? What if we extracted
them, either to the call sites directly or to separate (or wrapping) functions?

[BigBossZhiling, 2017/04/11 18:37:51]

Done.

+    history.pushState({suite: suite_name}, suite_name, '');
+  }
 }
 
-function showSuiteTableOnly() {
+function showSuiteTableOnly(replace_state) {
   setTitle('Suites Summary')
   showTestTable(false);
   showSuiteTable(true);
+  window.scrollTo(0, 0);
+  if (replace_state) {
+    history.replaceState({}, 'suite_table', '');
+  }
+}
+
+function setBrowserBackButtonLogic() {
+  window.onpopstate = function(event) {
+    if (!event.state || !event.state.suite) {
+      showSuiteTableOnly(false);
+    } else {
+      showTestsOfOneSuiteOnly(event.state.suite, false);
+    }
+  };
 }
 
 function setTitle(title) {
@@ -166,17 +184,6 @@ function sortByColumn(head) {
   }
 }
 
-function loadPage() {
-  var args = getArguments();
-  if ('suite' in args) {
-    // The user wants to visit detailed 'subpage' of that suite.
-    showTestsOfOneSuiteOnly(args['suite']);
-  } else {
-    // The user wants to visit the summary of all suites.
-    showSuiteTableOnly();
-  }
-}
-
 function reportIssues() {
   var url = 'https://bugs.chromium.org/p/chromium/issues/entry?' +
             'labels=Pri-2,Type-Bug,Restrict-View-Google&' +