Avoid stale navigation requests without excessive page id knowledge in the renderer process.

content/browser/frame_host/navigation_controller_impl.cc

 // Copyright 2013 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "content/browser/frame_host/navigation_controller_impl.h"
 
 #include "base/bind.h"
 #include "base/command_line.h"
 #include "base/debug/trace_event.h"
 #include "base/logging.h"
@@ skipping 1299 matching lines @@
 }
 
 void NavigationControllerImpl::CopyStateFromAndPrune(
     NavigationController* temp,
     bool replace_entry) {
   // It is up to callers to check the invariants before calling this.
   CHECK(CanPruneAllButLastCommitted());
 
   NavigationControllerImpl* source =
       static_cast<NavigationControllerImpl*>(temp);
-  // The SiteInstance and page_id of the last committed entry needs to be
-  // remembered at this point, in case there is only one committed entry
-  // and it is pruned.  We use a scoped_refptr to ensure the SiteInstance
-  // can't be freed during this time period.
-  NavigationEntryImpl* last_committed =
-      NavigationEntryImpl::FromNavigationEntry(GetLastCommittedEntry());
-  scoped_refptr<SiteInstance> site_instance(
-      last_committed->site_instance());
-  int32 minimum_page_id = last_committed->GetPageID();
-  int32 max_page_id =
-      delegate_->GetMaxPageIDForSiteInstance(site_instance.get());
 
-  // Remove all the entries leaving the active entry.
+  // Remove all the entries leaving the last committed entry.
   PruneAllButLastCommittedInternal();
 
   // We now have one entry, possibly with a new pending entry.  Ensure that
   // adding the entries from source won't put us over the limit.
   DCHECK_EQ(1, GetEntryCount());
   if (!replace_entry)
     source->PruneOldestEntryIfFull();
 
   // Insert the entries from source. Don't use source->GetCurrentEntryIndex as
-  // we don't want to copy over the transient entry.  Ignore any pending entry,
+  // we don't want to copy over the transient entry. Ignore any pending entry,
   // since it has not committed in source.
   int max_source_index = source->last_committed_entry_index_;
   if (max_source_index == -1)
     max_source_index = source->GetEntryCount();
   else
     max_source_index++;
 
   // Ignore the source's current entry if merging with replacement.
   // TODO(davidben): This should preserve entries forward of the current
   // too. http://crbug.com/317872
   if (replace_entry && max_source_index > 0)
     max_source_index--;
 
   InsertEntriesFrom(*source, max_source_index);
 
   // Adjust indices such that the last entry and pending are at the end now.
   last_committed_entry_index_ = GetEntryCount() - 1;
 
-  delegate_->SetHistoryLengthAndPrune(site_instance.get(),
-                                      max_source_index,
-                                      minimum_page_id);
+  delegate_->SetHistoryOffsetAndLength(last_committed_entry_index_,
+                                       GetEntryCount());
 
-  // Copy the max page id map from the old tab to the new tab.  This ensures
-  // that new and existing navigations in the tab's current SiteInstances
-  // are identified properly.
+  // Copy the max page id map from the old tab to the new tab. This ensures that
+  // new and existing navigations in the tab's current SiteInstances are
+  // identified properly.
+  NavigationEntryImpl* last_committed =
+      NavigationEntryImpl::FromNavigationEntry(GetLastCommittedEntry());
+  int32 site_max_page_id =
+      delegate_->GetMaxPageIDForSiteInstance(last_committed->site_instance());
   delegate_->CopyMaxPageIDsFrom(source->delegate()->GetWebContents());
+  delegate_->UpdateMaxPageIDForSiteInstance(last_committed->site_instance(),
+                                            site_max_page_id);
   max_restored_page_id_ = source->max_restored_page_id_;
-
-  // If there is a last committed entry, be sure to include it in the new
-  // max page ID map.
-  if (max_page_id > -1) {
-    delegate_->UpdateMaxPageIDForSiteInstance(site_instance.get(),
-                                              max_page_id);
-  }
 }
 
 bool NavigationControllerImpl::CanPruneAllButLastCommitted() {
   // If there is no last committed entry, we cannot prune.  Even if there is a
   // pending entry, it may not commit, leaving this WebContents blank, despite
   // possibly giving it new entries via CopyStateFromAndPrune.
   if (last_committed_entry_index_ == -1)
     return false;
 
   // We cannot prune if there is a pending entry at an existing entry index.
   // It may not commit, so we have to keep the last committed entry, and thus
   // there is no sensible place to keep the pending entry.  It is ok to have
   // a new pending entry, which can optionally commit as a new navigation.
   if (pending_entry_index_ != -1)
     return false;
 
   // We should not prune if we are currently showing a transient entry.
   if (transient_entry_index_ != -1)
     return false;
 
   return true;
 }
 
 void NavigationControllerImpl::PruneAllButLastCommitted() {
   PruneAllButLastCommittedInternal();
 
-  // We should still have a last committed entry.
-  DCHECK_NE(-1, last_committed_entry_index_);
+  DCHECK_EQ(0, last_committed_entry_index_);
+  DCHECK_EQ(1, GetEntryCount());
 
-  // We pass 0 instead of GetEntryCount() for the history_length parameter of
-  // SetHistoryLengthAndPrune, because it will create history_length additional
-  // history entries.
-  // TODO(jochen): This API is confusing and we should clean it up.
-  // http://crbug.com/178491
-  NavigationEntryImpl* entry =
-      NavigationEntryImpl::FromNavigationEntry(GetVisibleEntry());
-  delegate_->SetHistoryLengthAndPrune(
-      entry->site_instance(), 0, entry->GetPageID());
+  delegate_->SetHistoryOffsetAndLength(last_committed_entry_index_,
+                                       GetEntryCount());
 }
 
 void NavigationControllerImpl::PruneAllButLastCommittedInternal() {
   // It is up to callers to check the invariants before calling this.
   CHECK(CanPruneAllButLastCommitted());
 
   // Erase all entries but the last committed entry.  There may still be a
   // new pending entry after this.
   entries_.erase(entries_.begin(),
                  entries_.begin() + last_committed_entry_index_);
@@ skipping 365 matching lines @@
     }
   }
 }
 
 void NavigationControllerImpl::SetGetTimestampCallbackForTest(
     const base::Callback<base::Time()>& get_timestamp_callback) {
   get_timestamp_callback_ = get_timestamp_callback;
 }
 
 }  // namespace content