Browser Plugin: Implement CanGoBack/CanGoForward

content/renderer/browser_plugin/browser_plugin.cc

Index: content/renderer/browser_plugin/browser_plugin.cc
diff --git a/content/renderer/browser_plugin/browser_plugin.cc b/content/renderer/browser_plugin/browser_plugin.cc
index ed0f293678b2d13a4c5398ce6640fec90470115a..5581eeb2fe586a8b03397a0972e3ab6c8a47df89 100644
--- a/content/renderer/browser_plugin/browser_plugin.cc
+++ b/content/renderer/browser_plugin/browser_plugin.cc
@@ -72,7 +72,9 @@ BrowserPlugin::BrowserPlugin(
       navigate_src_sent_(false),
       process_id_(-1),
       persist_storage_(false),
-      visible_(true) {
+      visible_(true),
+      current_nav_entry_index_(0),
+      nav_entry_count_(0) {
   BrowserPluginManager::Get()->AddBrowserPlugin(instance_id, this);
   bindings_.reset(new BrowserPluginBindings(this));
 
@@ -149,6 +151,15 @@ std::string BrowserPlugin::GetPartitionAttribute() const {
   return value;
 }
 
+bool BrowserPlugin::CanGoBack() const {
+  return nav_entry_count_ > 1 && current_nav_entry_index_ > 0;
+}
+
+bool BrowserPlugin::CanGoForward() const {
+  return current_nav_entry_index_ >= 0 &&
+      current_nav_entry_index_ < (nav_entry_count_ - 1);
+}
+
 bool BrowserPlugin::SetPartitionAttribute(const std::string& partition_id,
                                           std::string& error_message) {
   if (navigate_src_sent_) {
@@ -337,6 +348,13 @@ void BrowserPlugin::GuestCrashed() {
   }
 }
 
+void BrowserPlugin::NavigationStateUpdate(int current_entry_index,
+                                          int entry_count) {
+  current_nav_entry_index_ = current_entry_index;
+  nav_entry_count_ = entry_count;
+}
+
+
 void BrowserPlugin::DidNavigate(const GURL& url, int process_id) {
   src_ = url.spec();
   process_id_ = process_id;