Add CombinedDesktopMediaList class

chrome/browser/media/tab_desktop_media_list.cc

+// Copyright 2016 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/media/tab_desktop_media_list.h"
+
+#include "base/hash.h"
+#include "chrome/browser/profiles/profile_manager.h"
+#include "chrome/browser/ui/browser.h"
+#include "chrome/browser/ui/browser_iterator.h"
+#include "chrome/browser/ui/tabs/tab_strip_model.h"
+#include "chrome/grit/generated_resources.h"
+#include "components/favicon/content/content_favicon_driver.h"
+#include "content/public/browser/browser_thread.h"
+#include "content/public/browser/render_frame_host.h"
+#include "content/public/browser/render_process_host.h"
+#include "third_party/skia/include/core/SkCanvas.h"
+#include "third_party/skia/include/core/SkImage.h"
+#include "ui/base/l10n/l10n_util.h"
+
+using content::DesktopMediaID;
+
+namespace {
+
+// Returns a hash of a favicon to detect when the favicon of media source has
+// changed.
+uint32_t GetImageHash(const gfx::Image& favicon) {
+  SkBitmap bitmap = favicon.AsBitmap();
+  bitmap.lockPixels();
+  uint32_t value = base::SuperFastHash(

[Sergey Ulanov, 2016/01/26 18:06:54]

Use base::Hash() instead of SuperFastHash().
Super-fast hash is a crappy hash function (it's not that fast and has many
collisions, see
http://programmers.stackexchange.com/questions/49550/which-hashing-algorithm-...)
and there is no reason to hard-code dependency on it here.

[GeorgeZ, 2016/01/27 00:17:38]

Done.

+      reinterpret_cast<char*>(bitmap.getPixels()), bitmap.getSize());
+  bitmap.unlockPixels();
+
+  return value;
+}
+
+gfx::ImageSkia CreateEnlargedFaviconImage(gfx::Size size, gfx::Image& favicon) {
+  if (size.width() < 20 || size.height() < 20)
+    return gfx::ImageSkia();

[Sergey Ulanov, 2016/01/26 18:06:54]

Why return an empty image here? Can this be a DCHECK? I don't think we expect
thumbnail size to be smaller than 20x20

[GeorgeZ, 2016/01/27 00:17:38]

Done.

+
+  // Create a bitmap.
+  SkBitmap result;
+  result.allocN32Pixels(size.width(), size.height(), true);
+  SkCanvas canvas(result);
+
+  // Fill with white.
+  canvas.drawARGB(255, 255, 255, 255);

[Sergey Ulanov, 2016/01/26 18:06:54]

Why is it white instead of transparent? This may not look right when the
background in the picker dialog isn't white

[GeorgeZ, 2016/01/27 00:17:38]

I modified as required. Please refer to
https://docs.google.com/document/d/1VaVZyT3NlvcFXD0q3-r8PAMVKYOMHw8CjGBSzwGnO...
for an example. 

+
+  // Draw black border.
+  const int thickness = result.width() / 30;
+  SkPaint paint;
+  paint.setARGB(255, 0, 0, 0);
+  paint.setStyle(SkPaint::kStroke_Style);
+  paint.setStrokeWidth(thickness);
+  canvas.drawRectCoords(thickness,                    // left
+                        thickness,                    // top
+                        result.width() - thickness,   // right
+                        result.height() - thickness,  // bottom
+                        paint);
+
+  // Draw a scaled favicon image into the center of result image to take up to
+  // 3/4 of result image.
+  const double scale = fmin(3.0 / 4 * result.width() / favicon.Width(),

[Sergey Ulanov, 2016/01/26 18:06:54]

std::min() instead of fmin()

[GeorgeZ, 2016/01/27 00:17:38]

Done.

+                            3.0 / 4 * result.height() / favicon.Height());
+  SkRect dest_rect;
+  dest_rect.set(result.width() / 2 - favicon.Width() * scale / 2,     // left

[Sergey Ulanov, 2016/01/26 18:06:54]

Combine this with the previous line:

SkRect dest_rect = SkRect::MakeLTRB(....);

[GeorgeZ, 2016/01/27 00:17:39]

Done.

+                result.height() / 2 - favicon.Height() * scale / 2,   // top
+                result.width() / 2 + favicon.Width() * scale / 2,     // right
+                result.height() / 2 + favicon.Height() * scale / 2);  // bottom
+  const scoped_ptr<SkImage> temp_image(

[Sergey Ulanov, 2016/01/26 18:06:54]

call it 'bitmap'? "temp_" doesn't make sense.

[GeorgeZ, 2016/01/27 00:17:38]

Done.

+      SkImage::NewFromBitmap(favicon.AsBitmap()));
+  canvas.drawImageRect(temp_image.get(), dest_rect, nullptr);
+
+  // Create a skia image.
+  return gfx::ImageSkia::CreateFrom1xBitmap(result);
+}
+
+// Update the list once per second.
+const int kDefaultUpdatePeriod = 1000;
+
+}  // namespace
+
+TabDesktopMediaList::TabDesktopMediaList()
+    : DesktopMediaListBase(
+          base::TimeDelta::FromMilliseconds(kDefaultUpdatePeriod)) {}
+
+TabDesktopMediaList::~TabDesktopMediaList() {}
+
+void TabDesktopMediaList::Refresh() {
+  DCHECK_CURRENTLY_ON(content::BrowserThread::UI);
+
+  std::map<DesktopMediaID, gfx::Image> favicon_map;
+  ImageHashesMap new_favicon_hashes;
+  std::vector<SourceDescription> sources;
+
+  if (!fake_sources_.size()) {
+    Profile* profile = ProfileManager::GetLastUsedProfileAllowedByPolicy();
+    std::vector<Browser*> browsers;
+    for (chrome::BrowserIterator it; !it.done(); it.Next()) {
+      if (it->profile()->GetOriginalProfile() == profile->GetOriginalProfile())
+        browsers.push_back(*it);
+    }
+
+    std::map<base::TimeTicks, SourceDescription> tab_map;
+
+    // Enumerate all tabs with their titles and favicons for a user profile.
+    for (auto browser : browsers) {
+      const TabStripModel* tab_strip_model = browser->tab_strip_model();
+      DCHECK(tab_strip_model);
+
+      for (int i = 0; i < tab_strip_model->count(); i++) {
+        // Create id for tab.
+        content::WebContents* contents = tab_strip_model->GetWebContentsAt(i);
+        DCHECK(contents);
+        content::RenderFrameHost* main_frame = contents->GetMainFrame();
+        DCHECK(main_frame);
+        DesktopMediaID media_id(
+            DesktopMediaID::TYPE_WEB_CONTENTS, DesktopMediaID::kNullId,
+            content::WebContentsMediaCaptureId(
+                main_frame->GetProcess()->GetID(), main_frame->GetRoutingID()));
+
+        // Create display tab title.
+        const base::string16 title = l10n_util::GetStringFUTF16(
+            IDS_DESKTOP_MEDIA_PICKER_CHROME_TAB_TITLE, contents->GetTitle());
+
+        // Get tab's last active time stamp.
+        const base::TimeTicks t = contents->GetLastActiveTime();
+        tab_map.insert(std::make_pair(t, SourceDescription(media_id, title)));

[qiangchen, 2016/01/26 01:01:50]

simpler to use [] operator?

[GeorgeZ, 2016/01/27 00:17:38]

struct SourceDescription does have default constructor. Therefore use [] will
lead to compile error.

+
+        // Get favicon for tab.
+        favicon::FaviconDriver* favicon_driver =
+            favicon::ContentFaviconDriver::FromWebContents(contents);
+        if (favicon_driver) {
+          gfx::Image favicon = favicon_driver->GetFavicon();
+          // Only new or changed favicon need update.
+          new_favicon_hashes[media_id] = GetImageHash(favicon);
+          if (!favicon_hashes_.count(media_id) ||
+              (favicon_hashes_[media_id] != new_favicon_hashes[media_id])) {
+            favicon_map.insert(

[qiangchen, 2016/01/26 01:01:50]

simpler to use []?
favicon_map[media_id] = favicon.

[GeorgeZ, 2016/01/27 00:17:38]

Done.

+                std::pair<DesktopMediaID, gfx::Image>(media_id, favicon));
+          }
+        }
+      }
+    }
+
+    // Sort tab sources by time. Most recent one first. Then update sources
+    // list.
+    for (auto it = tab_map.rbegin(); it != tab_map.rend(); ++it) {
+      SourceDescription& source = it->second;
+      sources.push_back(source);
+    }
+  } else {
+    // For unit tests.

[Sergey Ulanov, 2016/01/26 18:06:54]

This doesn't look like the right way to unittest this code. The unittests
execute almost no code that actually needs to be tested and the production code
is polluted with test-specific logic. I think it should be possible to create
fake profile with fake tabs in the unittests and then you wouldn't need
SetFakeSourcesForTesting()

[GeorgeZ, 2016/01/27 00:17:38]

Since tab related code will be removed from this CL, this issue will be
addressed in next cl.

+    for (size_t i = 0; i < fake_sources_.size(); i++) {
+      // Only new or changed favicon need update.
+      DesktopMediaID media_id = fake_sources_[i].id;
+      new_favicon_hashes[media_id] = GetImageHash(fake_favicons_[i]);
+      if (!favicon_hashes_.count(media_id) ||
+          (favicon_hashes_[media_id] != new_favicon_hashes[media_id])) {
+        favicon_map.insert(
+            std::pair<DesktopMediaID, gfx::Image>(media_id, fake_favicons_[i]));
+      }
+    }
+
+    sources = fake_sources_;
+  }
+  favicon_hashes_ = new_favicon_hashes;
+
+  UpdateSourcesList(sources);
+
+  for (auto it : favicon_map)
+    UpdateSourceThumbnail(
+        it.first, CreateEnlargedFaviconImage(thumbnail_size_, it.second));
+
+  ScheduleNextRefresh();
+}
+
+void TabDesktopMediaList::SetFakeSourcesForTesting(
+    std::vector<SourceDescription>& sources,
+    std::vector<gfx::Image>& favicons) {
+  fake_sources_ = sources;
+  fake_favicons_ = favicons;
+}