Don't show favicons or throbbers for the New Tab page on the Mac.

This change nets another 35ms (15%) improvement in the duration between the
renderer requesting the NTP and it having all of the resources for the NTP
available and being completely done with layout on my Mac laptop in release
mode.

For any page which DOMUI indicates no icon should be shown, including the New
Tab page, don't show a favicon or throbber.  When the icon is removed, the
title should expand to the left to fill the void.  Compare to the behavior on
Windows and Linux.

http://groups.google.com/group/chromium-dev/browse_thread/thread/7148074f807dc5f7

BUG=13337 20378
TEST=No throbber or favicon on the New Tab page
Review URL: http://codereview.chromium.org/184003

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@25167 0039d316-1c4b-4281-b951-d872f2087c98

1 files changed, 79 insertions, 24 deletions

diff --git a/chrome/browser/cocoa/tab_controller.mm b/chrome/browser/cocoa/tab_controller.mm
index 75f860d..231164a 100644
--- a/chrome/browser/cocoa/tab_controller.mm
+++ b/chrome/browser/cocoa/tab_controller.mm
@@ -21,10 +21,10 @@
 
 // The min widths match the windows values and are sums of left + right
 // padding, of which we have no comparable constants (we draw using paths, not
-// images). The selected tab width includes the close box width.
+// images). The selected tab width includes the close button width.
 + (float)minTabWidth { return 31; }
 + (float)minSelectedTabWidth { return 47; }
-+ (float)maxTabWidth { return 220.0; }
++ (float)maxTabWidth { return 220; }
 
 - (TabView*)tabView {
   return static_cast<TabView*>([self view]);
@@ -33,6 +33,7 @@
 - (id)init {
   self = [super initWithNibName:@"TabView" bundle:mac_util::MainAppBundle()];
   if (self != nil) {
+    isIconShowing_ = YES;
     [[NSNotificationCenter defaultCenter]
         addObserver:self
            selector:@selector(viewResized:)
@@ -59,9 +60,21 @@
 
 // Called when the tab's nib is done loading and all outlets are hooked up.
 - (void)awakeFromNib {
+  // Remember the icon's frame, so that if the icon is ever removed, a new
+  // one can later replace it in the proper location.
+  originalIconFrame_ = [iconView_ frame];
+
+  // When the icon is removed, the title expands to the left to fill the space
+  // left by the icon.  When the close button is removed, the title expands to
+  // the right to fill its space.  These are the amounts to expand and contract
+  // titleView_ under those conditions.
+  NSRect titleFrame = [titleView_ frame];
+  iconTitleXOffset_ = NSMinX(titleFrame) - NSMinX(originalIconFrame_);
+  titleCloseWidthOffset_ = NSMaxX([closeButton_ frame]) - NSMaxX(titleFrame);
+
   // Ensure we don't show favicon if the tab is already too small to begin with.
   [self updateVisibility];
-  [(id)iconView_ setImage:nsimage_cache::ImageNamed(@"nav.pdf")];
+
   [self internalSetSelected:selected_];
 }
 
@@ -103,13 +116,16 @@
 }
 
 - (void)setIconView:(NSView*)iconView {
-  NSRect currentFrame = [iconView_ frame];
   [iconView_ removeFromSuperview];
   iconView_ = iconView;
-  [iconView_ setFrame:currentFrame];
-  // Ensure we don't show favicon if the tab is already too small to begin with.
+  [iconView_ setFrame:originalIconFrame_];
+
+  // Ensure that the icon is suppressed if no icon is set or if the tab is too
+  // narrow to display one.
   [self updateVisibility];
-  [[self view] addSubview:iconView_];
+
+  if (iconView_)
+    [[self view] addSubview:iconView_];
 }
 
 - (NSView*)iconView {
@@ -124,42 +140,81 @@
 // tab. We never actually do this, but it's a helpful guide for determining
 // how much space we have available.
 - (int)iconCapacity {
-  float width = NSWidth([[self view] frame]);
-  float leftPadding = NSMinX([iconView_ frame]);
-  float rightPadding = width - NSMaxX([closeButton_ frame]);
-  float iconWidth = NSWidth([iconView_ frame]);
+  float width = NSMaxX([closeButton_ frame]) - NSMinX(originalIconFrame_);
+  float iconWidth = NSWidth(originalIconFrame_);
 
-  width -= leftPadding + rightPadding;
   return width / iconWidth;
 }
 
 // Returns YES if we should show the icon. When tabs get too small, we clip
-// the favicon before the close box for selected tabs, and prefer the favicon
-// for unselected tabs.
-// TODO(pinkerton): don't show the icon if there's no image data (eg, NTP).
+// the favicon before the close button for selected tabs, and prefer the
+// favicon for unselected tabs.  The icon can also be suppressed more directly
+// by clearing iconView_.
 - (BOOL)shouldShowIcon {
+  if (!iconView_)
+    return NO;
+
   int iconCapacity = [self iconCapacity];
   if ([self selected])
     return iconCapacity >= 2;
   return iconCapacity >= 1;
 }
 
-// Returns YES if we should be showing the close box. The selected tab always
-// shows the close box.
-- (BOOL)shouldShowCloseBox {
+// Returns YES if we should be showing the close button. The selected tab
+// always shows the close button.
+- (BOOL)shouldShowCloseButton {
   return [self selected] || [self iconCapacity] >= 3;
 }
 
-// Call to update the visibility of certain subviews, such as the icon or
-// close box, based on criteria like if the tab is selected and the current
-// tab width.
+// Updates the visibility of certain subviews, such as the icon and close
+// button, based on criteria such as the tab's selected state and its current
+// width.
 - (void)updateVisibility {
-  [iconView_ setHidden:[self shouldShowIcon] ? NO : YES];
-  [closeButton_ setHidden:[self shouldShowCloseBox] ? NO : YES];
+  // iconView_ may have been replaced or it may be nil, so [iconView_ isHidden]
+  // won't work.  Instead, the state of the icon is tracked separately in
+  // isIconShowing_.
+  BOOL oldShowIcon = isIconShowing_ ? YES : NO;
+  BOOL newShowIcon = [self shouldShowIcon] ? YES : NO;
+
+  [iconView_ setHidden:newShowIcon ? NO : YES];
+  isIconShowing_ = newShowIcon;
+
+  BOOL oldShowCloseButton = [closeButton_ isHidden] ? NO : YES;
+  BOOL newShowCloseButton = [self shouldShowCloseButton] ? YES : NO;
+
+  [closeButton_ setHidden:newShowCloseButton ? NO : YES];
+
+  // Adjust the title view based on changes to the icon's and close button's
+  // visibility.
+  NSRect titleFrame = [titleView_ frame];
+
+  if (oldShowIcon != newShowIcon) {
+    // Adjust the left edge of the title view according to the presence or
+    // absence of the icon view.
+
+    if (newShowIcon) {
+      titleFrame.origin.x += iconTitleXOffset_;
+      titleFrame.size.width -= iconTitleXOffset_;
+    } else {
+      titleFrame.origin.x -= iconTitleXOffset_;
+      titleFrame.size.width += iconTitleXOffset_;
+    }
+  }
+
+  if (oldShowCloseButton != newShowCloseButton) {
+    // Adjust the right edge of the title view according to the presence or
+    // absence of the close button.
+    if (newShowCloseButton)
+      titleFrame.size.width -= titleCloseWidthOffset_;
+    else
+      titleFrame.size.width += titleCloseWidthOffset_;
+  }
+
+  [titleView_ setFrame:titleFrame];
 }
 
 // Called when our view is resized. If it gets too small, start by hiding
-// the close box and only show it if tab is selected. Eventually, hide the
+// the close button and only show it if tab is selected. Eventually, hide the
 // icon as well. We know that this is for our view because we only registered
 // for notifications from our specific view.
 - (void)viewResized:(NSNotification*)info {