feat: customize border radius of Views (#42320)

* feat: add View#setBorderRadius

test: initial setBorderRadius tests

fix: robustly set border radius

chore: add PAUSE_CAPTURE_TESTS for easier screencap dev

feat: add view border radius support

test: view border radius

refactor: cleanup view code

* maybe delay capture to fix tests?

* refactor: retry screen captures in an attempt to fix flakiness

* refactor: ScreenCapture constructor no longer async

* increase screen capture timeout, feels a little short

* refactor: move rounded rect util into chromium_src

* skip some capture tests on mas

shell/browser/api/electron_api_web_contents_view.h

@@ -39,6 +39,7 @@ class WebContentsView : public View,
   // Public APIs.
   gin::Handle<WebContents> GetWebContents(v8::Isolate* isolate);
   void SetBackgroundColor(std::optional<WrappedSkColor> color);
+  void SetBorderRadius(int radius);
 
   int NonClientHitTest(const gfx::Point& point) override;
 
@@ -57,6 +58,8 @@ class WebContentsView : public View,
  private:
   static gin_helper::WrappableBase* New(gin_helper::Arguments* args);
 
+  void ApplyBorderRadius();
+
   // Keep a reference to v8 wrapper.
   v8::Global<v8::Value> web_contents_;
   raw_ptr<api::WebContents> api_web_contents_;