alternate ntp: implement searchbox api for instant overlay to adopt themes

chrome/browser/instant/instant_controller.cc

Index: chrome/browser/instant/instant_controller.cc
diff --git a/chrome/browser/instant/instant_controller.cc b/chrome/browser/instant/instant_controller.cc
index 4f8ba0185e950b99b5384f76fc52e08bb3158bb1..457b4ae01dc0b753454a8308a2a1f3d0386416e1 100644
--- a/chrome/browser/instant/instant_controller.cc
+++ b/chrome/browser/instant/instant_controller.cc
@@ -561,6 +561,16 @@ void InstantController::OnActiveTabModeChanged(chrome::search::Mode new_mode) {
   }
 }
 
+void InstantController::ThemeChanged(const ThemeBackgroundInfo& theme_info) {
+  if (GetPreviewContents())
+    loader_->SendThemeBackgroundInfo(theme_info);
+}
+
+void InstantController::ThemeAreaHeightChanged(int height) {
+  if (GetPreviewContents())
+    loader_->SendThemeAreaHeight(height);
+}
+
 bool InstantController::commit_on_pointer_release() const {
   return GetPreviewContents() && loader_->IsPointerDownFromActivate();
 }
@@ -692,8 +702,9 @@ void InstantController::ResetLoader(const std::string& instant_url,
     loader_.reset(new InstantLoader(this, instant_url, active_tab));
     loader_->Init();
 
-    // Ensure the searchbox API has the correct context.
+    // Ensure the searchbox API has the correct context and theme-related info.
     loader_->OnActiveTabModeChanged(active_tab_mode_.is_ntp());
+    browser_->UpdateThemeInfoForPreview();
 
     // Reset the loader timer.
     stale_loader_timer_.Stop();