Remove BackForwardClient, cleanup starting a history navigation

Source/web/FrameLoaderClientImpl.cpp

Index: Source/web/FrameLoaderClientImpl.cpp
diff --git a/Source/web/FrameLoaderClientImpl.cpp b/Source/web/FrameLoaderClientImpl.cpp
index 107504056be14563f79a833c878ac0f713516dbe..d62b941c168b23c1e93588f06d929e03f021aa15 100644
--- a/Source/web/FrameLoaderClientImpl.cpp
+++ b/Source/web/FrameLoaderClientImpl.cpp
@@ -540,9 +540,9 @@ bool FrameLoaderClientImpl::navigateBackForward(int offset) const
         return false;
 
     ASSERT(offset);
-    offset = std::min(offset, webview->client()->historyForwardListCount());
-    offset = std::max(offset, -webview->client()->historyBackListCount());

[Nate Chapin, 2014/10/22 19:57:18]

This min/max bounding is unnecessary. For backspace navigation, where the only
offsets are -1 and 1, bounding renders the navigation invalid by setting the
offset to 0. For normal back/forward navigations, we have always declared the
navigation invalid if the offset was out of bounds (in NavigationScheduler).

-    if (!offset)
+    if (offset > webview->client()->historyForwardListCount())
+        return false;
+    if (offset < -webview->client()->historyBackListCount())
         return false;
     webview->client()->navigateBackForwardSoon(offset);
     return true;
@@ -859,4 +859,12 @@ void FrameLoaderClientImpl::dispatchDidChangeManifest()
         m_webFrame->client()->didChangeManifest(m_webFrame);
 }
 
+unsigned FrameLoaderClientImpl::backForwardLength()
+{
+    WebViewImpl* webview = m_webFrame->viewImpl();
+    if (!webview || !webview->client())
+        return 0;
+    return webview->client()->historyBackListCount() + 1 + webview->client()->historyForwardListCount();
+}
+
 } // namespace blink