Update to Chromium revision 9cedf753 (#418732)

- Simplify usage of OnBeforePluginLoad (issue #2015)
- Switch crash reporting from crashpad to breakpad on Windows and OS X.
  Adds a new chrome_elf.dll dependency on Windows (issue #1995)
- Remove CefTextfield::GetPlaceholderTextColor() method which is no
  longer supported by Chromium.

libcef/browser/extensions/api/tabs/tabs_api.h

@@ -18,6 +18,14 @@ class WebContents;
 namespace extensions {
 namespace cef {
 
+class TabsGetFunction : public UIThreadExtensionFunction {
+  ~TabsGetFunction() override {}
+
+  ResponseAction Run() override;
+
+  DECLARE_EXTENSION_FUNCTION("tabs.get", TABS_GET)
+};
+
 class ZoomAPIFunction : public AsyncExtensionFunction {
  protected:
   ~ZoomAPIFunction() override {}