Update to Chromium version 70.0.3538.0 (#587811)

Known issues:
- The CefLoadCRLSetsFile function needs to be re-implemented (see issue #2497).
- Linux: GTK2 support has been removed. The cefclient sample needs to be updated
  to use GTK3 (see issue #2014).

tests/ceftests/osr_accessibility_unittest.cc

@@ -200,8 +200,6 @@ class AccessibilityTestHandler : public TestHandler,
       EXPECT_EQ(VTYPE_LIST, value->GetType());
       CefRefPtr<CefListValue> list = value->GetList();
       EXPECT_TRUE(list.get());
-      // Always empty events after https://crrev.com/c101cb728a.
-      EXPECT_EQ(0U, list->GetSize());
 
       got_accessibility_location_change_.yes();
     }