Add "Learn more" link in External storage preferences settings.

This adds "Learn more" link on
Settings > Device > Storage management > External storage preferences
for detailed explanations about the setting.

Bug: 1007188
Test: Manually tested on kevin.
Change-Id: I4774bc1051e32c994e937fafadc017f9196295de
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1820922
Commit-Queue: Naoki Fukino <fukino@chromium.org>
Reviewed-by: Michael Giuffrida <michaelpg@chromium.org>
Cr-Commit-Position: refs/heads/master@{#702327}

chrome/app/settings_strings.grdp

@@ -4837,7 +4837,7 @@
       External storage preferences
     </message>
     <message name="IDS_SETTINGS_STORAGE_ANDROID_APPS_ACCESS_EXTERNAL_DRIVES_NOTE" desc="Label for the additional note for the subpage for setting preferences for external storage.">
-      Apps from Google Play may require full file system access to read and write files on external storage devices. Files and folders created on the device are visible to anyone who uses the external drive.
+      Apps from Google Play may require full file system access to read and write files on external storage devices. Files and folders created on the device are visible to anyone who uses the external drive. <ph name="LINK_BEGIN">&lt;a target="_blank" href="$1<ex>https://google.com/</ex>"&gt;</ph>Learn more<ph name="LINK_END">&lt;/a&gt;</ph>
     </message>
     <message name="IDS_SETTINGS_STORAGE_EXTERNAL_STORAGE_LIST_HEADER" desc="Header of the list of external storage devices for the subpage for setting preferences for external storage.">
       Available devices will appear here.

chrome/browser/resources/settings/device_page/storage_external.html

@@ -15,7 +15,7 @@
     </style>
     <div class="settings-box first">
       <span>
-        $i18n{storageAndroidAppsExternalDrivesNote}
+        $i18nRaw{storageAndroidAppsExternalDrivesNote}
       </span>
     </div>
     <h2>$i18n{storageExternalStorageListHeader}</h2>

chrome/browser/ui/webui/settings/settings_localized_strings_provider.cc

@@ -1066,13 +1066,17 @@ void AddDeviceStrings(content::WebUIDataSource* html_source) {
       {"storageSpaceCriticallyLowMessageLine2",
        IDS_SETTINGS_STORAGE_SPACE_CRITICALLY_LOW_MESSAGE_LINE_2},
       {"storageExternal", IDS_SETTINGS_STORAGE_EXTERNAL},
-      {"storageAndroidAppsExternalDrivesNote",
-       IDS_SETTINGS_STORAGE_ANDROID_APPS_ACCESS_EXTERNAL_DRIVES_NOTE},
       {"storageExternalStorageListHeader",
        IDS_SETTINGS_STORAGE_EXTERNAL_STORAGE_LIST_HEADER}};
   AddLocalizedStringsBulk(html_source, kStorageStrings,
                           base::size(kStorageStrings));
 
+  html_source->AddString(
+      "storageAndroidAppsExternalDrivesNote",
+      l10n_util::GetStringFUTF16(
+          IDS_SETTINGS_STORAGE_ANDROID_APPS_ACCESS_EXTERNAL_DRIVES_NOTE,
+          base::ASCIIToUTF16(chrome::kArcExternalStorageLearnMoreURL)));
+
   static constexpr LocalizedString kPowerStrings[] = {
       {"powerTitle", IDS_SETTINGS_POWER_TITLE},
       {"powerSourceLabel", IDS_SETTINGS_POWER_SOURCE_LABEL},

chrome/common/url_constants.cc

@@ -273,6 +273,13 @@ const char kAccountManagerLearnMoreURL[] =
 const char kAndroidAppsLearnMoreURL[] =
     "https://support.google.com/chromebook/?p=playapps";
 
+const char kArcExternalStorageLearnMoreURL[] =
+    "https://support.google.com/chromebook?p=open_files";
+
+const char kArcPrivacyPolicyURLPath[] = "arc/privacy_policy";
+
+const char kArcTermsURLPath[] = "arc/terms";
+
 const char kChromeAccessibilityHelpURL[] =
     "https://support.google.com/chromebook/topic/6323347";
 
@@ -339,10 +346,6 @@ const char kNaturalScrollHelpURL[] =
 
 const char kOemEulaURLPath[] = "oem";
 
-const char kArcTermsURLPath[] = "arc/terms";
-
-const char kArcPrivacyPolicyURLPath[] = "arc/privacy_policy";
-
 const char kOnlineEulaURLPath[] =
     "https://www.google.com/intl/%s/chrome/eula_text.html";
 

chrome/common/url_constants.h

@@ -224,6 +224,18 @@ extern const char kAccountManagerLearnMoreURL[];
 // The URL for the "learn more" link for Google Play Store (ARC) settings.
 extern const char kAndroidAppsLearnMoreURL[];
 
+// The URL for the "Learn more" link in the External storage preferences
+// settings.
+extern const char kArcExternalStorageLearnMoreURL[];
+
+// The path format to the localized offline ARC++ Privacy Policy.
+// Relative to |kChromeOSAssetPath|.
+extern const char kArcPrivacyPolicyPathFormat[];
+
+// The path format to the localized offline ARC++ Terms of Service.
+// Relative to |kChromeOSAssetPath|.
+extern const char kArcTermsPathFormat[];
+
 // Accessibility help link for Chrome.
 extern const char kChromeAccessibilityHelpURL[];
 
@@ -247,14 +259,6 @@ extern const char kEasyUnlockLearnMoreUrl[];
 // The path to the offline Chrome OS EULA.
 extern const char kEULAPathFormat[];
 
-// The path format to the localized offline ARC++ Terms of Service.
-// Relative to |kChromeOSAssetPath|.
-extern const char kArcTermsPathFormat[];
-
-// The path format to the localized offline ARC++ Privacy Policy.
-// Relative to |kChromeOSAssetPath|.
-extern const char kArcPrivacyPolicyPathFormat[];
-
 // The URL for EOL notification
 extern const char kEolNotificationURL[];