Make sure to fill canvas opaquely when painting bookmark bar background.

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

Index: chrome/browser/ui/views/frame/browser_view.cc
diff --git a/chrome/browser/ui/views/frame/browser_view.cc b/chrome/browser/ui/views/frame/browser_view.cc
index bfb23b6c32151a007111121d3ec31ebea3c7dc66..81d85653d1e2c92dc4188fc390dfe6224f1ce757 100644
--- a/chrome/browser/ui/views/frame/browser_view.cc
+++ b/chrome/browser/ui/views/frame/browser_view.cc
@@ -223,17 +223,16 @@ void PaintHorizontalBorder(gfx::Canvas* canvas,
 // content page in the very near future, at which time, these local functions
 // will be removed.
 void PaintDetachedBookmarkBar(gfx::Canvas* canvas,
-                              BookmarkBarView* view,
-                              Profile* profile) {
+                              BookmarkBarView* view) {
   // Paint background for detached state; if animating, this is fade in/out.
-  const ui::ThemeProvider& tp =
-      ThemeService::GetThemeProviderForProfile(profile);
+  const ui::ThemeProvider* tp = view->GetThemeProvider();
   canvas->DrawColor(
-      tp.GetColor(ThemeProperties::COLOR_DETACHED_BOOKMARK_BAR_BACKGROUND));
+      tp->GetColor(ThemeProperties::COLOR_DETACHED_BOOKMARK_BAR_BACKGROUND));
+
   // Draw the separators above and below bookmark bar;
   // if animating, these are fading in/out.
   SkColor separator_color =
-      tp.GetColor(ThemeProperties::COLOR_DETACHED_BOOKMARK_BAR_SEPARATOR);
+      tp->GetColor(ThemeProperties::COLOR_DETACHED_BOOKMARK_BAR_SEPARATOR);
 
   if (ui::MaterialDesignController::IsModeMaterial()) {
     BrowserView::Paint1pxHorizontalLine(
@@ -262,8 +261,7 @@ void PaintBackgroundAttachedMode(gfx::Canvas* canvas,
                                  const ui::ThemeProvider* theme_provider,
                                  const gfx::Rect& bounds,
                                  const gfx::Point& background_origin) {
-  canvas->FillRect(bounds,
-                   theme_provider->GetColor(ThemeProperties::COLOR_TOOLBAR));
+  canvas->DrawColor(theme_provider->GetColor(ThemeProperties::COLOR_TOOLBAR));
 
   // Always tile the background image in pre-MD. In MD, only tile if there's a
   // non-default image.
@@ -424,6 +422,12 @@ BookmarkBarViewBackground::BookmarkBarViewBackground(
 
 void BookmarkBarViewBackground::Paint(gfx::Canvas* canvas,
                                       views::View* view) const {
+  // Start with a frame-colored canvas in case the attached/detached colors
+  // aren't opaque.
+  canvas->DrawColor(SK_ColorBLACK);
+  canvas->DrawColor(
+      view->GetThemeProvider()->GetColor(ThemeProperties::COLOR_FRAME));

[sky, 2016/04/07 18:23:45]

Shouldn't this route through BrowserNonClientFrameView::GetFrameColor? In fact
perhaps there should be a called on BrowserNonClientFrameView for this painting,
eg BrowserNonClientFrameView::PaintBackground(...).

[Evan Stade, 2016/04/07 19:30:24]

This comment led me to realize I was wrong about the frame being the background,
because it wouldn't make sense for the bar to change color based on the frame's
activation state. So then I found this[1] and I was able to confirm that if I
changed[2] to something weird like SK_ColorGREEN then I could see the green
shining through on this theme with the old, non-layered version of the bookmark
bar.

Thus the new patch starts by painting COLOR_CONTROL_BACKGROUND. (Getting a hold
of contents_container_ from here to call ->background()->Paint() on it is a bit
of a hassle.)

[1]
https://code.google.com/p/chromium/codesearch#chromium/src/chrome/browser/ui/...
[2]
https://code.google.com/p/chromium/codesearch#chromium/src/chrome/browser/ui/...

+
   int toolbar_overlap = bookmark_bar_view_->GetToolbarOverlap();
 
   SkAlpha detached_alpha = static_cast<SkAlpha>(
@@ -439,7 +443,7 @@ void BookmarkBarViewBackground::Paint(gfx::Canvas* canvas,
   // While animating, set opacity to cross-fade between attached and detached
   // backgrounds including their respective separators.
   canvas->SaveLayerAlpha(detached_alpha);
-  PaintDetachedBookmarkBar(canvas, bookmark_bar_view_, browser_->profile());
+  PaintDetachedBookmarkBar(canvas, bookmark_bar_view_);
   canvas->Restore();
 }