Confirm ongoing IME composition at the right render widget in response to mouse click/tap.

content/browser/renderer_host/render_widget_host_view_aura.cc

Index: content/browser/renderer_host/render_widget_host_view_aura.cc
diff --git a/content/browser/renderer_host/render_widget_host_view_aura.cc b/content/browser/renderer_host/render_widget_host_view_aura.cc
index f32a160fd36634978a9a359fab36757b551132f1..f2717837f6317cbee98b74b5caff5087fb362a24 100644
--- a/content/browser/renderer_host/render_widget_host_view_aura.cc
+++ b/content/browser/renderer_host/render_widget_host_view_aura.cc
@@ -2527,10 +2527,10 @@ bool RenderWidgetHostViewAura::NeedsMouseCapture() {
 void RenderWidgetHostViewAura::FinishImeCompositionSession() {
   if (!has_composition_text_)
     return;
-  // TODO(wjmaclean): can host_ ever be null?
-  if (host_) {
-    host_->ImeConfirmComposition(base::string16(), gfx::Range::InvalidRange(),
-                                 false);
+
+  if (!!text_input_manager_ && !!text_input_manager_->GetActiveWidget()) {
+    text_input_manager_->GetActiveWidget()->ImeConfirmComposition(
+        base::string16(), gfx::Range::InvalidRange(), false);
   }
   ImeCancelComposition();
 }