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..8e47fbc32e2c824da20702d8a5f5a4f68a993406 100644
--- a/build/android/pylib/results/presentation/javascript/main_html.js
+++ b/build/android/pylib/results/presentation/javascript/main_html.js
@@ -46,12 +46,38 @@ function showTestsOfOneSuiteOnly(suite_name) {
       });
   showTestTable(true);
   showSuiteTable(false);
+  window.scrollTo(0, 0);
+}
+
+function testTablePage(suite_name, push_state) {

[jbudorick, 2017/04/11 18:43:02]

My motivation w/ this suggestion was to eliminate the flag entirely. If a client
wants to push the state, they call this; otherwise, they call
showTestsOfOneSuiteOnly. (Same w/ suiteTablePage vs showSuiteTableOnly)

+  showTestsOfOneSuiteOnly(suite_name);
+  if (push_state) {
+    history.pushState({suite: suite_name}, suite_name, '');
+  }
 }
 
 function showSuiteTableOnly() {
   setTitle('Suites Summary')
   showTestTable(false);
   showSuiteTable(true);
+  window.scrollTo(0, 0);
+}
+
+function suiteTablePage(replace_state) {
+  showSuiteTableOnly();
+  if (replace_state) {
+    history.replaceState({}, 'suite_table', '');
+  }
+}
+
+function setBrowserBackButtonLogic() {
+  window.onpopstate = function(event) {
+    if (!event.state || !event.state.suite) {
+      suiteTablePage(false);
+    } else {
+      testTablePage(event.state.suite, false);
+    }
+  };
 }
 
 function setTitle(title) {
@@ -166,17 +192,6 @@ 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&' +