Update to Chromium revision 8cb76f56 (#307671)

- Linux/Mac: Load V8 initial snapshot from external bin files (see http://crbug.com/421063).
- Windows: 8.1 SDK is now required (issue #1470).
- Remove CefDOMDocument::GetSelectionStartNode and GetSelectionEndNode methods(see https://codereview.chromium.org/763043004).
- Rename internal namespace used in base headers to avoid linker conflicts with cef_sandbox.lib.

git-svn-id: https://chromiumembedded.googlecode.com/svn/trunk@1956 5089003a-bbd8-11dd-ad1f-f1f9622dbc98

libcef/browser/browser_host_impl.h

@@ -383,7 +383,8 @@ class CefBrowserHostImpl : public CefBrowserHost,
                           content::WebContents* new_contents) override;
   void DidNavigateMainFramePostCommit(
       content::WebContents* tab) override;
-  content::JavaScriptDialogManager* GetJavaScriptDialogManager() override;
+  content::JavaScriptDialogManager* GetJavaScriptDialogManager(
+      content::WebContents* source) override;
   void RunFileChooser(
       content::WebContents* tab,
       const content::FileChooserParams& params) override;