Create a prominent omnibox UI element to add pages to the app launcher.

chrome/browser/ui/views/location_bar/add_to_app_launcher_view.cc

+// Copyright 2014 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/location_bar/add_to_app_launcher_view.h"
+
+#include "base/command_line.h"
+#include "base/strings/utf_string_conversions.h"
+#include "chrome/browser/ui/views/location_bar/location_bar_view.h"
+#include "chrome/common/chrome_switches.h"
+#include "content/public/browser/web_contents.h"
+#include "grit/generated_resources.h"
+#include "grit/theme_resources.h"
+#include "ui/base/l10n/l10n_util.h"
+#include "ui/base/resource/resource_bundle.h"
+#include "ui/gfx/color_utils.h"
+#include "ui/views/controls/image_view.h"
+#include "ui/views/controls/label.h"
+#include "url/gurl.h"
+
+namespace {
+
+// TODO(benwells): Factorize common code between this and

[Peter Kasting, 2014/06/11 18:20:48]

Nit: Refactor (I don't think "factorize" is a word, though it sounds cool!)

[benwells, 2014/06/12 03:36:34]

Done. There goes my attempt to mint a new word...

+// ContentSettingImageView.
+const int kBackgroundImages[] = IMAGE_GRID(IDR_OMNIBOX_CONTENT_SETTING_BUBBLE);
+const int kStayOpenTimeMS = 3200;  // Time spent with animation fully open.
+
+const int kOpenTimeMS = 150;
+const int kAnimationDurationMS = (kOpenTimeMS * 2) + kStayOpenTimeMS;
+
+// Amount of padding at the edges of the bubble.  If |by_icon| is true, this
+// is the padding next to the icon; otherwise it's the padding next to the
+// label.  (We increase padding next to the label by the amount of padding
+// "built in" to the icon in order to make the bubble appear to have
+// symmetrical padding.)
+int GetBubbleOuterPadding(bool by_icon) {
+  return LocationBarView::kItemPadding - LocationBarView::kBubblePadding +
+         (by_icon ? 0 : LocationBarView::kIconInternalPadding);

[Peter Kasting, 2014/06/11 18:20:48]

nIT: Indent 4, not even (2 places)

[benwells, 2014/06/12 03:36:35]

Done.

+}
+
+int GetTotalSpacingWhileAnimating() {
+  return GetBubbleOuterPadding(true) + LocationBarView::kItemPadding +
+         GetBubbleOuterPadding(false);
+}
+
+}  // namespace
+
+AddToAppLauncherView::AddToAppLauncherView(LocationBarView* parent,
+                                           const gfx::FontList& font_list,
+                                           SkColor text_color,
+                                           SkColor parent_background_color)
+    : parent_(parent),
+      background_painter_(
+          views::Painter::CreateImageGridPainter(kBackgroundImages)),
+      icon_(new views::ImageView),
+      text_label_(new views::Label(base::string16(), font_list)),
+      slide_animator_(this) {
+  icon_->SetHorizontalAlignment(views::ImageView::LEADING);
+  icon_->SetImage(ui::ResourceBundle::GetSharedInstance().GetImageSkiaNamed(
+      IDR_BOOKMARK_BAR_APPS_SHORTCUT));
+  icon_->SetTooltipText(
+      base::UTF8ToUTF16(l10n_util::GetStringUTF8(IDS_ADD_TO_APP_LIST_HINT)));
+  AddChildView(icon_);
+
+  text_label_->SetVisible(false);
+  text_label_->SetEnabledColor(text_color);
+  // Calculate the actual background color for the label.  The background images
+  // are painted atop |parent_background_color|.  We grab the color of the
+  // middle pixel of the middle image of the background, which we treat as the
+  // representative color of the entire background (reasonable, given the
+  // current appearance of these images).  Then we alpha-blend it over the
+  // parent background color to determine the actual color the label text will
+  // sit atop.
+  const SkBitmap& bitmap(ui::ResourceBundle::GetSharedInstance()
+                             .GetImageSkiaNamed(kBackgroundImages[4])
+                             ->GetRepresentation(1.0f)
+                             .sk_bitmap());

[Peter Kasting, 2014/06/11 18:20:48]

Nit: Can you wrap this like the code in content_setting_image_view.cc it was
copied from?

[benwells, 2014/06/12 03:36:35]

Done.

+  SkAutoLockPixels pixel_lock(bitmap);
+  SkColor background_image_color =
+      bitmap.getColor(bitmap.width() / 2, bitmap.height() / 2);
+  // Tricky bit: We alpha blend an opaque version of |background_image_color|
+  // against |parent_background_color| using the original image grid color's
+  // alpha. This is because AlphaBlend(a, b, 255) always returns |a| unchanged
+  // even if |a| is a color with non-255 alpha.
+  text_label_->SetBackgroundColor(
+      color_utils::AlphaBlend(SkColorSetA(background_image_color, 255),
+                              parent_background_color,
+                              SkColorGetA(background_image_color)));
+  text_label_->SetHorizontalAlignment(gfx::ALIGN_LEFT);
+  text_label_->SetElideBehavior(gfx::TRUNCATE);
+  text_label_->SetText(base::UTF8ToUTF16(
+      l10n_util::GetStringUTF8(IDS_ADD_TO_APP_LIST_NOTIFICATION_TEXT)));
+  AddChildView(text_label_);
+
+  slide_animator_.SetSlideDuration(kAnimationDurationMS);
+  slide_animator_.SetTweenType(gfx::Tween::LINEAR);
+}
+
+AddToAppLauncherView::~AddToAppLauncherView() {
+}
+
+void AddToAppLauncherView::Update(content::WebContents* web_contents) {
+  SetVisible(false);

[Peter Kasting, 2014/06/11 18:20:48]

In the cases where we ultimately remain invisible, don't we want to stop the
animation as well?  This prevents something like:

* Animation starts in tab A
* User switches to tab B, which is currently loading, causing this view to
disappear
* Almost immediately, the load completes; now we see the trailing end of the
animation from tab A

[benwells, 2014/06/12 03:36:34]

Yep good catch. Done.

I think it will require further refinement to be less annoying when switching
between tabs which have it visible and tabs that don't, but I'll look at that if
we decide to go with this animatory thing (another new word!).

+
+  base::CommandLine* command_line = base::CommandLine::ForCurrentProcess();
+  if (!command_line->HasSwitch(switches::kEnableProminentURLAppFlow) ||
+      !command_line->HasSwitch(switches::kEnableStreamlinedHostedApps)) {

[Peter Kasting, 2014/06/11 18:20:48]

Nit: No {} (since you don't use {} on one-line bodies in other functions in this
file) (2 places)

[benwells, 2014/06/12 03:36:34]

There isn't a single statement if anymore, so kept the curlies.

+    return;
+  }
+
+  if (!web_contents || web_contents->IsLoading() ||

[Peter Kasting, 2014/06/11 18:20:48]

Nit: Personally I'd just combine this with the conditional above as I don't
think doing so decreases readability, up to you

[benwells, 2014/06/12 03:36:35]

Done.

+      !web_contents->GetLastCommittedURL().SchemeIsHTTPOrHTTPS()) {
+    return;
+  }
+
+  SetVisible(true);
+
+  if (!slide_animator_.is_animating()) {
+    text_label_->SetVisible(true);
+    slide_animator_.Show();
+  }
+}
+
+void AddToAppLauncherView::AnimationEnded(const gfx::Animation* animation) {
+  slide_animator_.Reset();
+  text_label_->SetVisible(false);
+  parent_->Layout();

[Peter Kasting, 2014/06/11 18:20:48]

Nit: I might replace these last two lines with "AnimationProgressed(animation);"
just in case more code is added to AnimationProgressed() later

[benwells, 2014/06/12 03:36:35]

Done.

+  parent_->SchedulePaint();
+}
+
+void AddToAppLauncherView::AnimationProgressed(
+    const gfx::Animation* animation) {
+  parent_->Layout();
+  parent_->SchedulePaint();
+}
+
+void AddToAppLauncherView::AnimationCanceled(const gfx::Animation* animation) {
+  AnimationEnded(animation);
+}
+
+gfx::Size AddToAppLauncherView::GetPreferredSize() const {
+  // Height will be ignored by the LocationBarView.
+  gfx::Size size(icon_->GetPreferredSize());
+  if (slide_animator_.is_animating()) {
+    double state = slide_animator_.GetCurrentValue();
+    // The fraction of the animation we'll spend animating the string into view,
+    // which is also the fraction we'll spend animating it closed; total
+    // animation (slide out, show, then slide in) is 1.0.
+    const double kOpenFraction =
+        static_cast<double>(kOpenTimeMS) / kAnimationDurationMS;
+    double size_fraction = 1.0;
+    if (state < kOpenFraction)
+      size_fraction = state / kOpenFraction;
+    if (state > (1.0 - kOpenFraction))
+      size_fraction = (1.0 - state) / kOpenFraction;
+    size.Enlarge(size_fraction * (text_label_->GetPreferredSize().width() +
+                                  GetTotalSpacingWhileAnimating()),

[Peter Kasting, 2014/06/11 18:20:48]

Nit: Slightly strange indenting, the original indenting in
content_setting_image_view.cc is probably better

[benwells, 2014/06/12 03:36:34]

That's clang format. I prefer this (the indenting helps my brain parse it) but
I'm not too bothered either way. Changed to the formatting in the original.

+                 0);
+    size.SetToMax(background_painter_->GetMinimumSize());
+  }
+  return size;
+}
+
+void AddToAppLauncherView::Layout() {
+  const int icon_width = icon_->GetPreferredSize().width();
+  icon_->SetBounds(
+      std::min((width() - icon_width) / 2, GetBubbleOuterPadding(true)),
+      0,
+      icon_width,
+      height());
+  text_label_->SetBounds(
+      icon_->bounds().right() + LocationBarView::kItemPadding,
+      0,
+      std::max(width() - GetTotalSpacingWhileAnimating() - icon_width, 0),
+      height());
+}
+
+void AddToAppLauncherView::OnPaintBackground(gfx::Canvas* canvas) {
+  if (slide_animator_.is_animating())
+    background_painter_->Paint(canvas, size());
+}