ui: Remove use of bitmaps when painting tab backgrounds.

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

Index: chrome/browser/ui/views/tabs/tab.h
diff --git a/chrome/browser/ui/views/tabs/tab.h b/chrome/browser/ui/views/tabs/tab.h
index 7b7bc644e81e50785ca15f69330a514f3126bb59..57611b74d6373c766ac44e43a346f7391eb6def8 100644
--- a/chrome/browser/ui/views/tabs/tab.h
+++ b/chrome/browser/ui/views/tabs/tab.h
@@ -12,6 +12,7 @@
 #include "base/gtest_prod_util.h"
 #include "base/macros.h"
 #include "base/memory/ref_counted.h"
+#include "cc/paint/paint_record.h"
 #include "chrome/browser/ui/views/tabs/tab_renderer_data.h"
 #include "ui/base/layout.h"
 #include "ui/gfx/animation/animation_delegate.h"
@@ -235,11 +236,24 @@ class Tab : public gfx::AnimationDelegate,
   // Paints a tab background using the image defined by |fill_id| at the
   // provided offset. If |fill_id| is 0, it will fall back to using the solid
   // color defined by the theme provider and ignore the offset.
-  void PaintTabBackgroundUsingFillId(gfx::Canvas* fill_canvas,
-                                     gfx::Canvas* stroke_canvas,
-                                     bool is_active,
-                                     int fill_id,
-                                     int y_offset);
+  void PaintTabBackground(gfx::Canvas* canvas,
+                          bool active,
+                          int fill_id,
+                          int y_offset,
+                          const gfx::Path* clip);
+
+  // Helper methods for PaintTabBackground.
+  void PaintTabBackgroundFill(gfx::Canvas* canvas,
+                              const gfx::Path& fill_path,
+                              bool active,
+                              bool hover,
+                              SkColor active_color,
+                              SkColor inactive_color,
+                              int fill_id,
+                              int y_offset);
+  void PaintTabBackgroundStroke(gfx::Canvas* canvas,
+                                const gfx::Path& fill_path,
+                                bool active);
 
   // Paints the pinned tab title changed indicator and |favicon_|. |favicon_|
   // may be null. |favicon_draw_bounds| is |favicon_bounds_| adjusted for rtl
@@ -355,6 +369,24 @@ class Tab : public gfx::AnimationDelegate,
   // and thus may be null.
   gfx::ImageSkia favicon_;
 
+  struct BackgroundCache {

[Peter Kasting, 2017/04/07 00:59:20]

Nit: I think the Google style guide requests that structs go atop the section,
even though I understand why you defined it down here next to the use of the
type.

[danakj, 2017/04/07 19:10:49]

yeh.. that seems unfortunate here. The guide says "Within each section,
generally prefer grouping similar kinds of declarations together" but its not
strictly always. I'd prefer to keep this where it is if you're okay with that. I
think it would reduce readability to move it.

[Peter Kasting, 2017/04/07 23:34:03]

It's OK to keep it here.  It'd be even better to move it into the .cc file
somehow, but not at the expense of having to create unique_ptrs for this type
for the members and do heap allocations.

+    BackgroundCache();
+    ~BackgroundCache();
+
+    // Parameters used to construct the PaintRecords.
+    float scale = 0.f;
+    gfx::Size size;
+    SkColor active_color;

[Peter Kasting, 2017/04/07 00:59:20]

Nit: If you're going to init |scale| in the declaration list I'd also init these
colors (which are really BTs as well).

[danakj, 2017/04/07 19:10:49]

Right, don't want to compare uninit things, even tho scale is enough to cause
the initial cache to not be value.

+    SkColor inactive_color;
+
+    // The PaintRecords being cached based on the above parameters.
+    sk_sp<cc::PaintRecord> fill_record;
+    sk_sp<cc::PaintRecord> stroke_record;
+  };
+
+  BackgroundCache background_active_cache_;
+  BackgroundCache background_inactive_cache_;
+
   DISALLOW_COPY_AND_ASSIGN(Tab);
 };