Correctly align tab and toolbar backgrounds with the frame background.

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

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "chrome/browser/ui/views/tabs/tab.h"
 
 #include <limits>
 
 #include "base/command_line.h"
 #include "base/debug/alias.h"
@@ skipping 607 matching lines @@
 int Tab::GetPinnedWidth() {
   return GetMinimumInactiveSize().width() +
          GetLayoutConstant(TAB_PINNED_CONTENT_WIDTH);
 }
 
 // static
 int Tab::GetImmersiveHeight() {
   return kImmersiveTabHeight;
 }
 
+// static
+int Tab::GetYOffsetForActiveTabBackground() {
+  // The computed value here is strangely less than the height of the area atop
+  // the tab that doesn't get a background painted; otherwise, we could compute
+  // the value by simply using GetLayoutInsets(TAB).top().  My suspicion is that
+  // originally there was some sort of off-by-one error in how this background
+  // was painted, and theme authors compensated; now we're stuck perpetuating it
+  // as a result.
+  return -GetLayoutConstant(TAB_TOP_EXCLUSION_HEIGHT) - 1;
+}
+
 ////////////////////////////////////////////////////////////////////////////////
 // Tab, AnimationDelegate overrides:
 
 void Tab::AnimationProgressed(const gfx::Animation* animation) {
   // Ignore if the pulse animation is being performed on active tab because
   // it repaints the same image. See |Tab::PaintTabBackground()|.
   if (animation == pulse_animation_.get() && IsActive())
     return;
   SchedulePaint();
 }
@@ skipping 485 matching lines @@
           bar_rect.x(), 0, left_eye_width, kImmersiveBarHeight);
       canvas->FillRect(left_eye_rect, kEyeColor);
     }
   }
 }
 
 void Tab::PaintTabBackground(gfx::Canvas* canvas) {
   const int kActiveTabFillId = IDR_THEME_TOOLBAR;
   const bool has_custom_image =
       GetThemeProvider()->HasCustomImage(kActiveTabFillId);
+  const int y_offset = GetYOffsetForActiveTabBackground();
   if (IsActive()) {
     PaintTabBackgroundUsingFillId(canvas, true, kActiveTabFillId,
-                                  has_custom_image, 0);
+                                  has_custom_image, y_offset);
   } else {
     if (pinned_title_change_animation_ &&
         pinned_title_change_animation_->is_animating())
       PaintInactiveTabBackgroundWithTitleChange(canvas);
     else
       PaintInactiveTabBackground(canvas);
 
     const double throb_value = GetThrobValue();
     if (throb_value > 0) {
       canvas->SaveLayerAlpha(gfx::ToRoundedInt(throb_value * 0xff),
                              GetLocalBounds());
       PaintTabBackgroundUsingFillId(canvas, true, kActiveTabFillId,
-                                    has_custom_image, 0);
+                                    has_custom_image, y_offset);
       canvas->Restore();
     }
   }
 }
 
 void Tab::PaintInactiveTabBackgroundWithTitleChange(gfx::Canvas* canvas) {
   const int kPinnedTitleChangeGradientRadius = 20;
   const float radius = kPinnedTitleChangeGradientRadius;
   double x = radius;
   int alpha = 255;
@@ skipping 21 matching lines @@
   bool has_custom_image;
   int fill_id = controller_->GetBackgroundResourceId(&has_custom_image);
   // Explicitly map the id so we cache correctly.
   const chrome::HostDesktopType host_desktop_type = GetHostDesktopType(this);
   fill_id = chrome::MapThemeImage(host_desktop_type, fill_id);
 
   // If the theme is providing a custom background image, then its top edge
   // should be at the top of the tab. Otherwise, we assume that the background
   // image is a composited foreground + frame image.
   const int y_offset = GetThemeProvider()->HasCustomImage(fill_id) ?
-      0 : background_offset_.y();
+      -GetLayoutConstant(TAB_TOP_EXCLUSION_HEIGHT) : background_offset_.y();
 
   // We only cache the image when it's the default image and we're not hovered,
   // to avoid caching a background image that isn't the same for all tabs.
   if (!has_custom_image && !hover_controller_.ShouldDraw()) {
     ui::ScaleFactor scale_factor =
         ui::GetSupportedScaleFactor(canvas->image_scale());
     gfx::ImageSkia cached_image(GetCachedImage(fill_id, size(), scale_factor));
     if (cached_image.width() == 0) {
       gfx::Canvas tmp_canvas(size(), canvas->image_scale(), false);
       PaintTabBackgroundUsingFillId(&tmp_canvas, false, fill_id, false,
@@ skipping 340 matching lines @@
                          const gfx::ImageSkia& image) {
   DCHECK_NE(scale_factor, ui::SCALE_FACTOR_NONE);
   ImageCacheEntry entry;
   entry.resource_id = resource_id;
   entry.scale_factor = scale_factor;
   entry.image = image;
   image_cache_->push_front(entry);
   if (image_cache_->size() > kMaxImageCacheSize)
     image_cache_->pop_back();
 }