CoreAnimation: Reduce VA usage by extra layers

chrome/browser/ui/cocoa/tab_contents/tab_contents_controller.mm

Index: chrome/browser/ui/cocoa/tab_contents/tab_contents_controller.mm
diff --git a/chrome/browser/ui/cocoa/tab_contents/tab_contents_controller.mm b/chrome/browser/ui/cocoa/tab_contents/tab_contents_controller.mm
index 7eb9a3a4a275171ba7c574ca7cd1c2f3761c5ff6..67a49a644229682c8e667b5aaf08aa11a16f3a10 100644
--- a/chrome/browser/ui/cocoa/tab_contents/tab_contents_controller.mm
+++ b/chrome/browser/ui/cocoa/tab_contents/tab_contents_controller.mm
@@ -6,6 +6,7 @@
 
 #include <utility>
 
+#include "base/command_line.h"
 #include "base/mac/scoped_nsobject.h"
 #include "chrome/browser/devtools/devtools_window.h"
 #import "chrome/browser/themes/theme_properties.h"
@@ -16,6 +17,8 @@
 #include "content/public/browser/web_contents.h"
 #include "content/public/browser/web_contents_observer.h"
 #include "content/public/browser/web_contents_view.h"
+#include "ui/base/cocoa/animation_utils.h"
+#include "ui/base/ui_base_switches.h"
 #include "ui/gfx/geometry/rect.h"
 
 using content::WebContents;
@@ -73,6 +76,8 @@ class FullscreenObserver : public WebContentsObserver {
  @private
   TabContentsController* delegate_;  // weak
 }
+
+- (NSColor*)computeBackgroundColor;
 @end
 
 @implementation TabContentsContainerView
@@ -80,6 +85,14 @@ class FullscreenObserver : public WebContentsObserver {
 - (id)initWithDelegate:(TabContentsController*)delegate {
   if ((self = [super initWithFrame:NSZeroRect])) {
     delegate_ = delegate;
+    if (!CommandLine::ForCurrentProcess()->HasSwitch(
+            switches::kDisableCoreAnimation)) {
+      ScopedCAActionDisabler disabler;
+      base::scoped_nsobject<CALayer> layer([[CALayer alloc] init]);
+      [layer setBackgroundColor:CGColorGetConstantColor(kCGColorWhite)];
+      [self setLayer:layer];
+      [self setWantsLayer:YES];
+    }
   }
   return self;
 }
@@ -90,24 +103,28 @@ class FullscreenObserver : public WebContentsObserver {
   delegate_ = nil;
 }
 
+// Fill with a dark tint of the new tab page's background color.  This is
+// only seen when the subview is sized specially for fullscreen tab capture.
+- (NSColor*)computeBackgroundColor {
+  NSColor* bgColor = nil;
+  ThemeService* const theme =
+      static_cast<ThemeService*>([[self window] themeProvider]);
+  if (theme)
+    bgColor = theme->GetNSColor(ThemeProperties::COLOR_NTP_BACKGROUND);
+  if (!bgColor)
+    bgColor = [[self window] backgroundColor];
+  const float kDarknessFraction = 0.80f;
+  return [bgColor blendedColorWithFraction:kDarknessFraction
+                                   ofColor:[NSColor blackColor]];
+}
+
 // Override -drawRect to fill the view with a solid color outside of the
 // subview's frame.
 - (void)drawRect:(NSRect)dirtyRect {
   NSView* const contentsView =
       [[self subviews] count] > 0 ? [[self subviews] objectAtIndex:0] : nil;
   if (!contentsView || !NSContainsRect([contentsView frame], dirtyRect)) {
-    // Fill with a dark tint of the new tab page's background color.  This is
-    // only seen when the subview is sized specially for fullscreen tab capture.
-    NSColor* bgColor = nil;
-    ThemeService* const theme =
-        static_cast<ThemeService*>([[self window] themeProvider]);
-    if (theme)
-      bgColor = theme->GetNSColor(ThemeProperties::COLOR_NTP_BACKGROUND);
-    if (!bgColor)
-      bgColor = [[self window] backgroundColor];
-    const float kDarknessFraction = 0.80f;
-    [[bgColor blendedColorWithFraction:kDarknessFraction
-                               ofColor:[NSColor blackColor]] setFill];
+    [[self computeBackgroundColor] setFill];
     NSRectFill(dirtyRect);
   }
   [super drawRect:dirtyRect];
@@ -125,6 +142,24 @@ class FullscreenObserver : public WebContentsObserver {
   [contentsView setFrame:[delegate_ frameForContentsView]];
 }
 
+// Update the background layer's color whenever the view needs to repaint.
+- (void)setNeedsDisplayInRect:(NSRect)rect {
+  [super setNeedsDisplayInRect:rect];
+

[ccameron, 2014/04/19 02:45:29]

[NSColor CGColor] is a 10.8+ function.

Not sure if a helper function is preferred or not (not for this change, cause it
needs to be merged, but I can add a TODO & do it after).

[Avi (use Gerrit), 2014/04/19 19:30:49]

That's fine. With 10.6, they changed things so that you could assign an NSImage
for a layer's image, so I'm a bit surprised that you can't assign an NSColor
here and have it work.

+  // Convert from an NSColor to a CGColorRef.
+  NSColor* nsBackgroundColor = [self computeBackgroundColor];
+  NSColorSpace* nsColorSpace = [nsBackgroundColor colorSpace];
+  CGColorSpaceRef cgColorSpace = [nsColorSpace CGColorSpace];
+  const NSInteger numberOfComponents = [nsBackgroundColor numberOfComponents];
+  CGFloat components[numberOfComponents];
+  [nsBackgroundColor getComponents:components];
+  CGColorRef cgBackgroundColor = CGColorCreate(cgColorSpace, components);

[Avi (use Gerrit), 2014/04/19 19:30:49]

ScopedCFObject if you must go this route.

[ccameron, 2014/04/19 22:21:39]

Done.

+
+  ScopedCAActionDisabler disabler;
+  [[self layer] setBackgroundColor:cgBackgroundColor];
+  CGColorRelease(cgBackgroundColor);
+}
+
 @end  // @implementation TabContentsContainerView
 
 @implementation TabContentsController