Hide browser frame when using WebUITabStrip

When the WebUI-based tab strip replaces the views-based one no caption
buttons are drawn there's no content to be drawn in the browser frame.

The changes are restricted to BrowserView::IsBrowserTypeNormal() as
other window types might need draw something else (like PWA titles).

Bug: chromium:1005563
Change-Id: I5251a002ffd301d30a1db524ec560dd0aa3288c3
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1854804
Commit-Queue: Peter Boström <pbos@chromium.org>
Reviewed-by: Taylor Bergquist <tbergquist@chromium.org>
Cr-Commit-Position: refs/heads/master@{#705325}

chrome/browser/ui/views/frame/browser_non_client_frame_view_ash.cc

@@ -22,6 +22,7 @@
 #include "base/command_line.h"
 #include "base/metrics/user_metrics.h"
 #include "base/strings/utf_string_conversions.h"
+#include "build/build_config.h"
 #include "chrome/app/chrome_command_ids.h"
 #include "chrome/browser/platform_util.h"
 #include "chrome/browser/profiles/profiles_state.h"
@@ -31,6 +32,7 @@
 #include "chrome/browser/ui/browser.h"
 #include "chrome/browser/ui/browser_command_controller.h"
 #include "chrome/browser/ui/layout_constants.h"
+#include "chrome/browser/ui/ui_features.h"
 #include "chrome/browser/ui/views/frame/browser_frame.h"
 #include "chrome/browser/ui/views/frame/browser_view.h"
 #include "chrome/browser/ui/views/frame/immersive_mode_controller.h"
@@ -649,6 +651,15 @@ int BrowserNonClientFrameViewAsh::GetTabStripRightInset() const {
 }
 
 bool BrowserNonClientFrameViewAsh::ShouldPaint() const {
+#if BUILDFLAG(ENABLE_WEBUI_TAB_STRIP)
+  // Normal windows that have a WebUI-based tab strip do not need a browser
+  // frame as no tab strip is drawn on top of the browser frame.
+  if (base::FeatureList::IsEnabled(features::kWebUITabStrip) &&
+      browser_view()->IsBrowserTypeNormal()) {
+    return false;
+  }
+#endif  // BUILDFLAG(ENABLE_WEBUI_TAB_STRIP)
+
   // We need to paint when the top-of-window views are revealed in immersive
   // fullscreen.
   ImmersiveModeController* immersive_mode_controller =

chrome/browser/ui/views/frame/top_controls_slide_controller_chromeos_browsertest.cc

@@ -259,11 +259,6 @@ class TopControlsSlideControllerTest : public InProcessBrowserTest {
   }
 
   // InProcessBrowserTest:
-  void SetUp() override {
-    scoped_feature_list_.InitAndEnableFeature(features::kWebUITabStrip);
-    InProcessBrowserTest::SetUp();
-  }
-
   void SetUpDefaultCommandLine(base::CommandLine* command_line) override {
     InProcessBrowserTest::SetUpDefaultCommandLine(command_line);
 
@@ -452,8 +447,6 @@ class TopControlsSlideControllerTest : public InProcessBrowserTest {
     return std::move(controller);
   }
 
-  base::test::ScopedFeatureList scoped_feature_list_;
-
   TestController* test_controller_ = nullptr;  // Not owned.
 
   DISALLOW_COPY_AND_ASSIGN(TopControlsSlideControllerTest);
@@ -1209,4 +1202,6 @@ IN_PROC_BROWSER_TEST_F(TopControlsSlideControllerTest, TestToggleChromeVox) {
                                TopChromeShownState::kFullyHidden);
 }
 
+// TODO(crbug.com/989131): Add test coverage that covers using WebUITabStrip.
+
 }  // namespace