A step by step guide to upgrade webview on an old Android Emulator

README.md

Tools

1. emulator (30.3.5) (via Android SDK)
2. adb (30.0.5) (via Android SDK)
3. apktool (2.5.0) and Java runtime
4. zip (3.0)
5. unzip (6.0)

Make sure you have JAVA_HOME and ANDROID_HOME environment variables correctly set.

Steps

1. Create a new Android Virtual Device (AVD) using Android Studio or avdmanager. Here, I created an Android 5.0 device with the following system image:

   Path                                        | Version | Description                                | Location
   system-images;android-21;google_apis;x86_64 | 32      | Google APIs Intel x86 Atom_64 System Image | system-images/android-21/google_apis/x86_64/

   The AVD name is

   $ emulator -list-avds
   Pixel_2_API_21

2. Boot the AVD and make its system partition writable:

   $ $ANDROID_HOME/tools/emulator @Pixel_2_API_21 -writable-system

   And the AVD starts, remount its system partition using adb:

   $ $ANDROID_HOME/platform-tools/adb remount

3. Download the Android System Webview of your desired version from the internet. For example, you may use Android System WebView 88.0.4324.93 (x86 + x86_64) (Android 5.0+) from apkmirror.com. The package ID is com.google.android.webview, which is different from the default system webview (com.android.webview). Also, make sure your package has the same ABI as your AVD.

4. Extract the webview package using unzip and push it and the native libraries to the system partition of your AVD:

   $ unzip <path/to/your/webview.apk>
   $ $ANDROID_HOME/platform-tools/adb shell mkdir /system/app/ChromiumWebview
   $ $ANDROID_HOME/platform-tools/adb push <path/to/your/webview.apk> /system/app/ChromiumWebview/webview.apk
   $ $ANDROID_HOME/platform-tools/adb push <path/to/your/extracted/webview.apk>/lib /system/app/ChromiumWebview/

   After this step is done, you should have the following new files in your AVD:

   $ANDROID_HOME/platform-tools/adb shell ls -lR /system/app/ChromiumWebview/lib                                                            ✔ 
   
   /system/app/ChromiumWebview/lib:
   drwxr-xr-x root     root              2021-01-27 00:36 x86
   drwxr-xr-x root     root              2021-01-27 00:36 x86_64
   
   /system/app/ChromiumWebview/lib/x86:
   -rw-r--r-- root     root        43360 1979-12-31 00:00 libchromium_android_linker.so
   -rw-r--r-- root     root         3680 1979-12-31 00:00 libcrashpad_handler_trampoline.so
   -rw-r--r-- root     root     78167008 1979-12-31 00:00 libwebviewchromium.so
   
   /system/app/ChromiumWebview/lib/x86_64:
   -rw-r--r-- root     root        44896 1979-12-31 00:00 libchromium_android_linker.so
   -rw-r--r-- root     root         5104 1979-12-31 00:00 libcrashpad_handler_trampoline.so
   -rw-r--r-- root     root     78545528 1979-12-31 00:00 libwebviewchromium.so

5. Restart Android services to let the Package Manager pick up our new webview package:

   $ $ANDROID_HOME/platform-tools/adb shell stop
   $ $ANDROID_HOME/platform-tools/adb shell start
   $ $ANDROID_HOME/platform-tools/adb shell pm list packages | grep webview
   package:com.android.webview           --> the built-in and outdated webview
   package:com.google.android.webview    --> our new webview

6. Check if the package is registered with the Package Manager. Make sure codePath, nativeLibraryPath, and primaryCpuAbi are correct:

   $ $ANDROID_HOME/platform-tools/adb shell cat /data/system/packages.xml | grep com.google.android.webview
   <package name="com.google.android.webview" codePath="/system/app/ChromiumWebview" nativeLibraryPath="/system/app/ChromiumWebview/lib" primaryCpuAbi="x86_64" secondaryCpuAbi="x86" flags="...

7. As the default webview package name used by the Android OS is hard-coded in older Android OSes (https://android.stackexchange.com/a/139415), you need to modify the Android framework to use the new package name. First, pull framework-res.apk from your AVD and decompile it using apktool:

   $ $ANDROID_HOME/platform-tools/adb pull /system/framework/framework-res.apk
   $ apktool d framework-res.apk

8. Update the <path/to/extracted/framework-res.apk>/res/values/strings.xml file to use your new system webview package name:

   --- res/values/strings.xml	2021-01-27 00:53:05.000000000 -0500
   +++ res/values/strings.xml	2021-01-27 00:54:38.000000000 -0500
   @@ -70,7 +70,7 @@
        <string name="config_appsAuthorizedForSharedAccounts">;com.android.settings;</string>
        <string name="config_defaultNetworkScorerPackageName" />
        <string name="config_persistentDataPackageName" />
   -    <string name="config_webViewPackageName">com.android.webview</string>
   +    <string name="config_webViewPackageName">com.google.android.webview</string>
        <item type="string" name="timepicker_circle_radius_multiplier">0.82</item>
        <item type="string" name="timepicker_circle_radius_multiplier_24HourMode">0.85</item>
        <item type="string" name="timepicker_selection_radius_multiplier">0.16</item>

9. Repack framework-res.apk using apktool.

   $ apktool b <path/to/extracted/framework-res.apk>

   There might be a few errors you need to fix before the package can be repacked. For example, if you encountered the following error:

   Error: String types not allowed (at 'APKTOOL_DUMMY_34e' with value '').
   

   you should replace <drawable name="APKTOOL_DUMMY_..." /> with <item type="drawable" name="APKTOOL_DUMMY_..." /> in the <path/to/extracted/framework-res.apk>/res/values-nodpi-v4/drawables.xml file and retry.

10. The repacked framework-res.apk is placed under <path/to/extracted/framework-res.apk>/dist. Extract the resources.arsc file from it and merge it to the original framework-res.apk:

    $ unzip <path/to/extracted/framework-res.apk>/dist/framework-res.apk resources.arsc -d .
    $ zip -0 <path/to/original/framework-res.apk> resources.arsc

    The original framework-res.apk you pulled from your AVD is now updated.

11. Next, replace the framework-res.apk in your AVD with our updated (merged) framework-res.apk from last step and reboot device:

    $ $ANDROID_HOME/platform-tools/adb push <path/to/original/framework-res.apk> /system/framework/framework-res.apk
    $ $ANDROID_HOME/platform-tools/adb reboot

12. Finally, check if the webview is switched to the new one:

    

To upgrade the Android WebView version, I downloaded the Chrome APK within Android using the terminal. This approach allows updating the WebView component without modifying the system files directly.