Add compile time checks against longs being used in IPC structs on 32 bit Android.

content/renderer/text_input_client_observer.cc

Index: content/renderer/text_input_client_observer.cc
diff --git a/content/renderer/text_input_client_observer.cc b/content/renderer/text_input_client_observer.cc
index eda58f206f1d58ac61d3f2f3a0187a2adb263faf..b97be4a31bd5497b3a58e2a91615a93c90cda472 100644
--- a/content/renderer/text_input_client_observer.cc
+++ b/content/renderer/text_input_client_observer.cc
@@ -65,7 +65,8 @@ void TextInputClientObserver::OnStringAtPoint(gfx::Point point) {
 
 void TextInputClientObserver::OnCharacterIndexForPoint(gfx::Point point) {
   blink::WebPoint web_point(point);
-  size_t index = webview()->focusedFrame()->characterIndexForPoint(web_point);
+  uint32_t index = static_cast<uint32_t>(
+      webview()->focusedFrame()->characterIndexForPoint(web_point));
   Send(new TextInputClientReplyMsg_GotCharacterIndexForPoint(routing_id(),
       index));
 }