[Favicon] Adding chrome://fallback-icon host for Fallback Icon "Explicit Flow"

Design: go/chrome-fallback-icons

We're chrome://fallback-icon host, managed by FallbackIconSource, so we can
specify URLs such as
  chrome://fallback-icon/128,#f00,black,0.8,0.1/http://www.google.com
to render a fallback icon. This is useful for testing fallback icons.

This CL is sliced off from https://codereview.chromium.org/835903005/ .

BUG=455063

Review URL: https://codereview.chromium.org/973883002

Cr-Commit-Position: refs/heads/master@{#319333}

8 files changed, 164 insertions, 1 deletions

diff --git a/chrome/browser/search/instant_service.cc b/chrome/browser/search/instant_service.cc
index f02d656..e785e0c 100644
--- a/chrome/browser/search/instant_service.cc
+++ b/chrome/browser/search/instant_service.cc
@@ -19,6 +19,7 @@
 #include "chrome/browser/themes/theme_service_factory.h"
 #include "chrome/browser/thumbnails/thumbnail_list_source.h"
 #include "chrome/browser/ui/search/instant_search_prerenderer.h"
+#include "chrome/browser/ui/webui/fallback_icon_source.h"
 #include "chrome/browser/ui/webui/favicon_source.h"
 #include "chrome/browser/ui/webui/ntp/thumbnail_source.h"
 #include "chrome/browser/ui/webui/theme_source.h"
@@ -124,6 +125,7 @@ InstantService::InstantService(Profile* profile)
   content::URLDataSource::Add(profile_, new ThumbnailListSource(profile_));
 #endif  // !defined(OS_ANDROID)
 
+  content::URLDataSource::Add(profile_, new FallbackIconSource());
   content::URLDataSource::Add(
       profile_, new FaviconSource(profile_, FaviconSource::FAVICON));
   content::URLDataSource::Add(profile_, new MostVisitedIframeSource());
diff --git a/chrome/browser/ui/webui/fallback_icon_source.cc b/chrome/browser/ui/webui/fallback_icon_source.cc
new file mode 100644
index 0000000..78eae81
--- /dev/null
+++ b/chrome/browser/ui/webui/fallback_icon_source.cc
@@ -0,0 +1,83 @@
+// Copyright 2015 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/webui/fallback_icon_source.h"
+
+#include <string>
+#include <vector>
+
+#include "base/memory/ref_counted_memory.h"
+#include "chrome/browser/search/instant_io_context.h"
+#include "chrome/common/favicon/fallback_icon_url_parser.h"
+#include "chrome/common/url_constants.h"
+#include "grit/platform_locale_settings.h"
+#include "net/url_request/url_request.h"
+#include "ui/base/l10n/l10n_util.h"
+#include "ui/gfx/favicon_size.h"
+
+FallbackIconSource::FallbackIconSource() {
+  std::vector<std::string> font_list;
+#if defined(OS_CHROMEOS)
+  font_list.push_back("Noto Sans");
+#elif defined(OS_IOS)
+  font_list.push_back("Helvetica Neue");
+#else
+  font_list.push_back(l10n_util::GetStringUTF8(IDS_SANS_SERIF_FONT_FAMILY));
+#endif
+  fallback_icon_service_.reset(
+      new favicon_base::FallbackIconService(font_list));
+}
+
+FallbackIconSource::~FallbackIconSource() {
+}
+
+std::string FallbackIconSource::GetSource() const {
+  return chrome::kChromeUIFallbackIconHost;
+}
+
+void FallbackIconSource::StartDataRequest(
+    const std::string& path,
+    int render_process_id,
+    int render_frame_id,
+    const content::URLDataSource::GotDataCallback& callback) {
+  chrome::ParsedFallbackIconPath parsed;
+  bool success = parsed.Parse(path);
+  if (!success) {
+    SendDefaultResponse(callback);
+    return;
+  }
+
+  GURL url(parsed.url());
+  std::vector<unsigned char> bitmap_data =
+      fallback_icon_service_->RenderFallbackIconBitmap(
+          url, parsed.size_in_pixels(), parsed.style());
+  callback.Run(base::RefCountedBytes::TakeVector(&bitmap_data));
+}
+
+std::string FallbackIconSource::GetMimeType(const std::string&) const {
+  // We need to explicitly return a mime type, otherwise if the user tries to
+  // drag the image they get no extension.
+  return "image/png";
+}
+
+bool FallbackIconSource::ShouldReplaceExistingSource() const {
+  // Leave the existing DataSource in place, otherwise we'll drop any pending
+  // requests on the floor.
+  return false;
+}
+
+bool FallbackIconSource::ShouldServiceRequest(
+    const net::URLRequest* request) const {
+  if (request->url().SchemeIs(chrome::kChromeSearchScheme))
+    return InstantIOContext::ShouldServiceRequest(request);
+  return URLDataSource::ShouldServiceRequest(request);
+}
+
+void FallbackIconSource::SendDefaultResponse(
+    const content::URLDataSource::GotDataCallback& callback) {
+  std::vector<unsigned char> bitmap_data =
+      fallback_icon_service_->RenderFallbackIconBitmap(
+          GURL(), gfx::kFaviconSize, favicon_base::FallbackIconStyle());
+  callback.Run(base::RefCountedBytes::TakeVector(&bitmap_data));
+}
diff --git a/chrome/browser/ui/webui/fallback_icon_source.h b/chrome/browser/ui/webui/fallback_icon_source.h
new file mode 100644
index 0000000..086bbd0
--- /dev/null
+++ b/chrome/browser/ui/webui/fallback_icon_source.h
@@ -0,0 +1,69 @@
+// Copyright 2015 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.
+
+#ifndef CHROME_BROWSER_UI_WEBUI_FALLBACK_ICON_SOURCE_H_
+#define CHROME_BROWSER_UI_WEBUI_FALLBACK_ICON_SOURCE_H_
+
+#include "base/memory/scoped_ptr.h"
+#include "components/favicon_base/fallback_icon_service.h"
+#include "content/public/browser/url_data_source.h"
+
+// FallbackIconSource services explicit chrome:// requests for fallback icons.
+//
+// Format:
+//   chrome://fallback-icon/size,bc,tc,fsr,r/url
+// All of the parameters except for the url are optional. However, the order of
+// the parameters is not interchangeable, and all "," must be in place.
+//
+// Parameter:
+//  'size'
+//    Positive integer to specify the fallback icon's size in pixels.
+//  'bc'
+//    Fallback icon's background color, as named CSS color, or #RGB / #RRGGBB /
+//    #AARRGGBB hex formats.
+//  'tc'
+//    Fallback icon text color, as named CSS color, or #RGB / #RRGGBB /
+//    #AARRGGBB hex formats.
+//  'fsr'
+//    Number in [0.0, 1.0] to specify the fallback icon's font size (pixels)
+//    as a ratio to the icon's size.
+//  'r'
+//    Number in [0.0, 1.0] to specify the fallback icon's roundness.
+//    0.0 specifies a square icon; 1.0 specifies a circle icon; intermediate
+//    values specify a rounded square icon.
+//  'url'
+//    String to specify the page URL of the fallback icon.
+//
+//  Example: chrome://fallback-icon/32,red,#000,0.5,1.0/http://www.google.com/
+//    This requests a 32x32 fallback icon for http://www.google.com, using
+//    red as the background color, #000 as the text color, with font size of
+//    32 * 0.5 = 16, and the icon's background shape is a circle.
+class FallbackIconSource : public content::URLDataSource {
+ public:
+  FallbackIconSource();
+
+  ~FallbackIconSource() override;
+
+  // content::URLDataSource implementation.
+  std::string GetSource() const override;
+  void StartDataRequest(
+      const std::string& path,
+      int render_process_id,
+      int render_frame_id,
+      const content::URLDataSource::GotDataCallback& callback) override;
+  std::string GetMimeType(const std::string&) const override;
+  bool ShouldReplaceExistingSource() const override;
+  bool ShouldServiceRequest(const net::URLRequest* request) const override;
+
+ private:
+  // Sends the default fallback icon.
+  void SendDefaultResponse(
+      const content::URLDataSource::GotDataCallback& callback);
+
+  scoped_ptr<favicon_base::FallbackIconService> fallback_icon_service_;
+
+  DISALLOW_COPY_AND_ASSIGN(FallbackIconSource);
+};
+
+#endif  // CHROME_BROWSER_UI_WEBUI_FALLBACK_ICON_SOURCE_H_
diff --git a/chrome/browser/ui/webui/ntp/most_visited_handler.cc b/chrome/browser/ui/webui/ntp/most_visited_handler.cc
index 16d5b7c..39a1f2f 100644
--- a/chrome/browser/ui/webui/ntp/most_visited_handler.cc
+++ b/chrome/browser/ui/webui/ntp/most_visited_handler.cc
@@ -27,6 +27,7 @@
 #include "chrome/browser/ui/browser_finder.h"
 #include "chrome/browser/ui/tabs/tab_strip_model.h"
 #include "chrome/browser/ui/tabs/tab_strip_model_utils.h"
+#include "chrome/browser/ui/webui/fallback_icon_source.h"
 #include "chrome/browser/ui/webui/favicon_source.h"
 #include "chrome/browser/ui/webui/ntp/new_tab_ui.h"
 #include "chrome/browser/ui/webui/ntp/ntp_stats.h"
@@ -79,6 +80,9 @@ void MostVisitedHandler::RegisterMessages() {
   // Set up our sources for top-sites data.
   content::URLDataSource::Add(profile, new ThumbnailListSource(profile));
 
+  // Register chrome://fallback-icon as a data source for fallback icons.
+  content::URLDataSource::Add(profile, new FallbackIconSource());
+
   // Register chrome://favicon as a data source for favicons.
   content::URLDataSource::Add(
       profile, new FaviconSource(profile, FaviconSource::FAVICON));
diff --git a/chrome/chrome_browser_ui.gypi b/chrome/chrome_browser_ui.gypi
index 435420d..902f9ed 100644
--- a/chrome/chrome_browser_ui.gypi
+++ b/chrome/chrome_browser_ui.gypi
@@ -1040,6 +1040,8 @@
       'browser/ui/webui/device_log_ui.h',
       'browser/ui/webui/domain_reliability_internals_ui.cc',
       'browser/ui/webui/domain_reliability_internals_ui.h',
+      'browser/ui/webui/fallback_icon_source.cc',
+      'browser/ui/webui/fallback_icon_source.h',
       'browser/ui/webui/favicon_source.cc',
       'browser/ui/webui/favicon_source.h',
       'browser/ui/webui/fileicon_source.cc',
diff --git a/chrome/common/url_constants.cc b/chrome/common/url_constants.cc
index 3dc3a47..cf5f17e 100644
--- a/chrome/common/url_constants.cc
+++ b/chrome/common/url_constants.cc
@@ -45,6 +45,7 @@ const char kChromeUIEditSearchEngineDialogURL[] = "chrome://editsearchengine/";
 const char kChromeUIExtensionIconURL[] = "chrome://extension-icon/";
 const char kChromeUIExtensionsFrameURL[] = "chrome://extensions-frame/";
 const char kChromeUIExtensionsURL[] = "chrome://extensions/";
+const char kChromeUIFallbackIconURL[] = "chrome://fallback-icon/";
 const char kChromeUIFaviconURL[] = "chrome://favicon/";
 const char kChromeUIFeedbackURL[] = "chrome://feedback/";
 const char kChromeUIFlagsURL[] = "chrome://flags/";
@@ -186,6 +187,7 @@ const char kChromeUIEditSearchEngineDialogHost[] = "editsearchengine";
 const char kChromeUIExtensionIconHost[] = "extension-icon";
 const char kChromeUIExtensionsFrameHost[] = "extensions-frame";
 const char kChromeUIExtensionsHost[] = "extensions";
+const char kChromeUIFallbackIconHost[] = "fallback-icon";
 const char kChromeUIFaviconHost[] = "favicon";
 const char kChromeUIFeedbackHost[] = "feedback";
 const char kChromeUIFlagsHost[] = "flags";
diff --git a/chrome/common/url_constants.h b/chrome/common/url_constants.h
index a161d58..7d4a1c7 100644
--- a/chrome/common/url_constants.h
+++ b/chrome/common/url_constants.h
@@ -40,6 +40,7 @@ extern const char kChromeUIEditSearchEngineDialogURL[];
 extern const char kChromeUIExtensionIconURL[];
 extern const char kChromeUIExtensionsFrameURL[];
 extern const char kChromeUIExtensionsURL[];
+extern const char kChromeUIFallbackIconURL[];
 extern const char kChromeUIFaviconURL[];
 extern const char kChromeUIFeedbackURL[];
 extern const char kChromeUIFlagsURL[];
@@ -177,6 +178,7 @@ extern const char kChromeUIEditSearchEngineDialogHost[];
 extern const char kChromeUIExtensionIconHost[];
 extern const char kChromeUIExtensionsFrameHost[];
 extern const char kChromeUIExtensionsHost[];
+extern const char kChromeUIFallbackIconHost[];
 extern const char kChromeUIFaviconHost[];
 extern const char kChromeUIFeedbackHost[];
 extern const char kChromeUIFlagsHost[];
diff --git a/components/favicon_base/fallback_icon_service.cc b/components/favicon_base/fallback_icon_service.cc
index 1642b20..adce72e 100644
--- a/components/favicon_base/fallback_icon_service.cc
+++ b/components/favicon_base/fallback_icon_service.cc
@@ -11,7 +11,6 @@
 #include "components/favicon_base/fallback_icon_style.h"
 #include "net/base/registry_controlled_domains/registry_controlled_domain.h"
 #include "third_party/skia/include/core/SkPaint.h"
-#include "ui/base/l10n/l10n_util.h"
 #include "ui/gfx/canvas.h"
 #include "ui/gfx/codec/png_codec.h"
 #include "ui/gfx/font_list.h"