Add a TabStyleHighlightPathGenerator to Tab

Replaces probably a significant amount of path updates in
::OnBoundsChanged override (which this change also removes).

This might reduce some jank in the tab strip while opening tabs or
resizing windows, though it's unclear whether it amounts to a
significant chunk of work as a fraction of total work here.

Bug: chromium:1007546
Change-Id: I5aab0ce9cfcaeea2bec80f994d0586e588ff977e
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1861044
Auto-Submit: Peter Boström <pbos@chromium.org>
Commit-Queue: Elly Fong-Jones <ellyjones@chromium.org>
Reviewed-by: Elly Fong-Jones <ellyjones@chromium.org>
Cr-Commit-Position: refs/heads/master@{#705971}

chrome/browser/ui/views/tabs/tab.cc

@@ -72,6 +72,7 @@
 #include "ui/resources/grit/ui_resources.h"
 #include "ui/views/border.h"
 #include "ui/views/controls/button/image_button.h"
+#include "ui/views/controls/highlight_path_generator.h"
 #include "ui/views/controls/label.h"
 #include "ui/views/rect_based_targeting_utils.h"
 #include "ui/views/view.h"
@@ -114,6 +115,22 @@ int Center(int size, int item_size) {
   return extra_space / 2;
 }
 
+class TabStyleHighlightPathGenerator : public views::HighlightPathGenerator {
+ public:
+  explicit TabStyleHighlightPathGenerator(TabStyle* tab_style)
+      : tab_style_(tab_style) {}
+
+  // views::HighlightPathGenerator:
+  SkPath GetHighlightPath(const views::View* view) override {
+    return tab_style_->GetPath(TabStyle::PathType::kHighlight, 1.0);
+  }
+
+ private:
+  TabStyle* const tab_style_;
+
+  DISALLOW_COPY_AND_ASSIGN(TabStyleHighlightPathGenerator);
+};
+
 }  // namespace
 
 // Helper class that observes the tab's close button.
@@ -206,6 +223,8 @@ Tab::Tab(TabController* controller)
   // Enable keyboard focus.
   SetFocusBehavior(FocusBehavior::ACCESSIBLE_ONLY);
   focus_ring_ = views::FocusRing::Install(this);
+  views::HighlightPathGenerator::Install(
+      this, std::make_unique<TabStyleHighlightPathGenerator>(tab_style_.get()));
 }
 
 Tab::~Tab() {
@@ -400,12 +419,6 @@ const char* Tab::GetClassName() const {
   return kViewClassName;
 }
 
-void Tab::OnBoundsChanged(const gfx::Rect& previous_bounds) {
-  // Update focus ring path.
-  const SkPath path = tab_style_->GetPath(TabStyle::PathType::kHighlight, 1.0);
-  SetProperty(views::kHighlightPathKey, path);
-}
-
 bool Tab::OnKeyPressed(const ui::KeyEvent& event) {
   if (event.key_code() == ui::VKEY_SPACE && !IsSelected()) {
     controller_->SelectTab(this, event);

chrome/browser/ui/views/tabs/tab.h

@@ -79,7 +79,6 @@ class Tab : public gfx::AnimationDelegate,
   // TabSlotView:
   void Layout() override;
   const char* GetClassName() const override;
-  void OnBoundsChanged(const gfx::Rect& previous_bounds) override;
   bool OnKeyPressed(const ui::KeyEvent& event) override;
   bool OnMousePressed(const ui::MouseEvent& event) override;
   bool OnMouseDragged(const ui::MouseEvent& event) override;