Making answer card to behave like other results.

chrome/browser/ui/app_list/search_answer_web_contents_delegate.cc

Index: chrome/browser/ui/app_list/search_answer_web_contents_delegate.cc
diff --git a/chrome/browser/ui/app_list/search_answer_web_contents_delegate.cc b/chrome/browser/ui/app_list/search_answer_web_contents_delegate.cc
index d9ba2e5622d3dc1883112802bb3f3d0c50ceed1a..8899d26a29e4b8c2f3ef2df989bd33213c8382d9 100644
--- a/chrome/browser/ui/app_list/search_answer_web_contents_delegate.cc
+++ b/chrome/browser/ui/app_list/search_answer_web_contents_delegate.cc
@@ -13,6 +13,8 @@
 #include "chrome/browser/ui/browser_navigator_params.h"
 #include "content/public/browser/navigation_handle.h"
 #include "content/public/browser/render_view_host.h"
+#include "content/public/browser/render_widget_host.h"
+#include "content/public/browser/render_widget_host_view.h"
 #include "content/public/browser/web_contents.h"
 #include "content/public/browser/web_contents_delegate.h"
 #include "content/public/common/renderer_preferences.h"
@@ -159,6 +161,14 @@ void SearchAnswerWebContentsDelegate::Update() {
 
   // We are going to call WebContents::GetPreferredSize().
   web_contents_->GetRenderViewHost()->EnablePreferredSizeMode();
+
+  // Make the webview transparent since it's going to be shown on top of a
+  // highlightable button.
+  content::RenderWidgetHostView* render_view_host_view =
+      web_contents_->GetRenderViewHost()->GetWidget()->GetView();
+  // The RenderWidgetHostView may be null if the renderer has crashed.
+  if (render_view_host_view)
+    render_view_host_view->SetBackgroundColor(SK_ColorTRANSPARENT);

[xiyuan, 2017/05/25 16:42:53]

There might be a few edge cases. We had WebContentsSetBackgroundColor [1] that
can be used for this. Can we move it to a common place and use it here as well ?

[1]:
https://cs.chromium.org/chromium/src/chrome/browser/chromeos/login/ui/web_con...

[vadimt, 2017/05/25 20:15:16]

Done.

 }
 
 void SearchAnswerWebContentsDelegate::UpdatePreferredSize(
@@ -168,8 +178,7 @@ void SearchAnswerWebContentsDelegate::UpdatePreferredSize(
       IsCardSizeOk(pref_size) || features::IsAnswerCardDarkRunEnabled();
   model_->SetSearchAnswerAvailable(is_card_size_ok_ && received_answer_ &&
                                    !web_contents_->IsLoading());
-  if (!features::IsAnswerCardDarkRunEnabled())
-    web_view_->SetPreferredSize(pref_size);
+  web_view_->SetPreferredSize(pref_size);
   if (!answer_loaded_time_.is_null()) {
     UMA_HISTOGRAM_TIMES("SearchAnswer.ResizeAfterLoadTime",
                         base::TimeTicks::Now() - answer_loaded_time_);