[Android] Add phone progress bar animation behind a flag.

chrome/common/chrome_switches.cc

Index: chrome/common/chrome_switches.cc
diff --git a/chrome/common/chrome_switches.cc b/chrome/common/chrome_switches.cc
index 341537775997c7107ed76ac4e0798330ac29e266..0ac8508c1f0920330c0ce4c1f28cae143152af64 100644
--- a/chrome/common/chrome_switches.cc
+++ b/chrome/common/chrome_switches.cc
@@ -1215,6 +1215,9 @@ const char kEnableZeroSuggestMostVisitedWithoutSerp[] =
 // Triggers prerendering of search base page to prefetch results for the typed
 // omnibox query. Only has an effect when prerender is enabled.
 const char kPrefetchSearchResults[]         = "prefetch-search-results";
+
+// Specifies Android phone page loading progress bar animation.
+const char kProgressBarAnimation[]          = "progress-bar-animation";
 #endif  // defined(OS_ANDROID)
 
 #if defined(USE_ASH)