Android: Add APK patch size estimates to resource_sizes.py.

build/android/binary_size/apks/README.md

Index: build/android/binary_size/apks/README.md
diff --git a/build/android/binary_size/apks/README.md b/build/android/binary_size/apks/README.md
new file mode 100644
index 0000000000000000000000000000000000000000..474ba93c432ec01a39ea9581baf48de93e94bd58
--- /dev/null
+++ b/build/android/binary_size/apks/README.md
@@ -0,0 +1,24 @@
+### Updating APKs in this folder (for new milestones, builders, or APKs)
+
+1. Find the commit as close as possible to the current branch point (i.e. if the
+latest builds are m59, we want to compare to the commit before the m58 branch
+point).
+
+2. Download and unzip build artifacts from the relevant perf builder. You can
+use this link:
+[https<nolink>://storage.cloud.google.com/chrome-perf/**Android%20Builder**/full-build-linux_**3a87aecc31cd1ffe751dd72c04e5a96a1fc8108a**.zip](https://storage.cloud.google.com/chrome-perf/Android%20Builder/full-build-linux_3a87aecc31cd1ffe751dd72c04e5a96a1fc8108a.zip)
+, replacing the bolded parts with your info OR from the
+"gsutil upload_build_product" step on the bot page (both are Googlers only).
+
+3. Upload the apk: _upload_to_google_storage.py --bucket
+'chromium-android-tools/apks/**Android_Builder**/**58**'
+**path/to/ApkTarget.apk**_ replacing the bolded parts again.
+  * Note that we use **Android_Builder** instead of **Android Builder** (replace
+spaces with underscores)
+
+4. Move the generated .sha1 file to the corresponding place in
+//build/android/binary_size/apks/. In this case, the path would be
+//build/android/binary_size/apks/Android_Builder/58
+
+5. Commit the added .sha1 files and (optionally) update the `CURRENT_MILESTONE`
+in apk_downloader.py