dragon: Modify DragonKeyboardFirmwareUpdater notification messages

This CL addresses the UI messages translation requirement.

BUG=25369339
TEST=build

Change-Id: Ic7e235475904f1cf86cb70ade59299a8e08a387a
diff --git a/DragonKeyboardFirmwareUpdater/dfu/res/values/strings.xml b/DragonKeyboardFirmwareUpdater/dfu/res/values/strings.xml
index 23dc6cf..22f9e8e 100644
--- a/DragonKeyboardFirmwareUpdater/dfu/res/values/strings.xml
+++ b/DragonKeyboardFirmwareUpdater/dfu/res/values/strings.xml
@@ -1,14 +1,37 @@
 <resources xmlns:xliff="urn:oasis:names:tc:xliff:document:1.2">
 
-    <string name="dfu_unknown_name">Unnamed device</string>
-    <string name="dfu_action_cancel">Cancel</string>
+    <!-- A placeholder name for when the keyboard's name cannot be
+         resolved.
+    -->
+    <string name="dfu_unknown_name" translatable="false">Unnamed device</string>
 
-    <!-- Pixel C Keyboard firmware update notification messages -->
+    <!-- This text is shown above the installation progress bar, and is meant to
+         act as a label for it (eg: "PRODUCT_NAME Keyboard update" is 18% done).
+    -->
     <string name="dfu_status_notification_updating_title"><xliff:g id="product_name">Pixel C</xliff:g> Keyboard update</string>
+
+    <!-- The notification message shown after the keyboard update is installed
+         successfully.
+    -->
     <string name="dfu_status_notification_update_finished_title"><xliff:g id="product_name">Pixel C</xliff:g> Keyboard update installed</string>
+
+    <!-- The notification message shown when the keyboard update doesn't
+         complete successfully, because the user canceled it.
+    -->
     <string name="dfu_status_notification_update_canceled_title"><xliff:g id="product_name">Pixel C</xliff:g> Keyboard update canceled</string>
+
+    <!-- The notification message shown when the keyboard update doesn't
+         complete successfully, because of technical failures (eg: the keyboard
+         is disconnected).
+    -->
     <string name="dfu_status_notification_update_failed_title"><xliff:g id="product_name">Pixel C</xliff:g> Keyboard update did not succeed</string>
 
     <string name="dfu_status_notification_updating_msg"><xliff:g id="update_progress_percent">%1$d %%</xliff:g></string>
 
+    <!-- button provided on the installation progress notification, which shows
+         up while the keyboard is being updated. If the user taps on this button, the
+         installation process is canceled.
+    -->
+    <string name="dfu_action_cancel">Cancel</string>
+
 </resources>
diff --git a/DragonKeyboardFirmwareUpdater/keyboard_firmware_updater/res/values/strings.xml b/DragonKeyboardFirmwareUpdater/keyboard_firmware_updater/res/values/strings.xml
index 8595996..330931d 100644
--- a/DragonKeyboardFirmwareUpdater/keyboard_firmware_updater/res/values/strings.xml
+++ b/DragonKeyboardFirmwareUpdater/keyboard_firmware_updater/res/values/strings.xml
@@ -15,7 +15,10 @@
 -->
 <resources xmlns:xliff="urn:oasis:names:tc:xliff:document:1.2">
 
-    <!-- Service name (for user) -->
+    <!-- This is the name of the keyboard updater service. It is shown in
+         Settings > Apps and when the user activates the Recents view while in the
+         installation confirmation screen.
+    -->
     <string name="app_name">
         <xliff:g id="product_name">Pixel C</xliff:g> Keyboard Firmware Updater
     </string>
@@ -30,19 +33,44 @@
     <string name="target_firmware_init_file_name" translatable="false">init_151104_mp_signed</string>
     <string name="target_firmware_image_file_name" translatable="false">image_151104_mp_signed</string>
 
-    <!-- Update notification texts (for users) -->
+    <!-- The notification message title shown when a keyboard update is
+         available. Users are given the option to install or postpone the update.
+    -->
     <string name="notification_title">Keyboard update available</string>
+
+    <!-- The notification message subtitle shown when a keyboard update is
+         available. It elaborates more on the title of the notification
+         ("Keyboard update available") by specifying the product name. Users are
+         given the option to install or postpone the update.
+    -->
     <string name="notification_text">
-        <xliff:g id="product_name">Pixel C</xliff:g> keyboard update is ready
+        <xliff:g id="product_name">Pixel C</xliff:g> Keyboard update is ready
     </string>
+
+    <!-- One of the two options provided by the "keyboard update available"
+         notification. Tapping on this option will dismiss the notification, and
+         the notification is expected to resurface again some time later.
+    -->
     <string name="notification_later">LATER</string>
+
+    <!-- One of the two options provided by the "keyboard update available"
+         notification. Tapping on this option will send users to the installation
+         screen.
+    -->
     <string name="notification_install">INSTALL</string>
 
-    <!-- UpdateConfirmationActivity messages (for users) -->
+    <!-- The text shown in the installation confirmation screen. The most
+         important points to convey to the user are that the keyboard will not work
+         during the update, and that they should not disconnect it during the
+         process.
+    -->
     <string name="confirmation_update_info">The keyboard will not work while it is updating.\nThis will take about 3 minutes.\n\nPlease do not disconnect the keyboard before the update completes.\n</string>
-    <string name="confirmation_install">INSTALL</string>
 
-    <!-- Update preference names (for service use)-->
+    <!-- A button provided on the installation confirmation screen. Tapping on
+         this will begin the installation process.
+    -->
+    <string name="confirmation_install">INSTALL</string>
+    <!-- Update preference names (for service use) -->
     <string name="preference_notification_flag" translatable="false">com.android.dragonkeyboardfirmwareupdater.preference_notification_flag</string>
     <string name="preference_current_version" translatable="false">com.android.dragonkeyboardfirmwareupdater.preference_current_version</string>