android: significantly increase emulator image screen sizes.

Fixes at least one test in content_browsertests that was increasing the
minimum frame size above the current screen width. New screen dimensions
roughly match the dimensions of the N5, N5X, and P2.

Bug: 922145
Change-Id: Iaf7fca25bfc56abfedd647dcc80fdb378a7ab5ca
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2033685Reviewed-by: Ben Pastene <bpastene@chromium.org>
Commit-Queue: John Budorick <jbudorick@chromium.org>
Cr-Commit-Position: refs/heads/master@{#737496}

tools/android/avd/proto/generic_android23.textpb

@@ -25,6 +25,11 @@ avd_package {
 avd_name: "android_23_google_apis_x86"
 
 avd_settings {
+  screen {
+    density: 480
+    height: 1920
+    width: 1080
+  }
   sdcard {
     size: "1G"
   }

tools/android/avd/proto/generic_android28.textpb

@@ -26,8 +26,8 @@ avd_name: "android_28_google_apis_x86"
 
 avd_settings {
   screen {
-    density: 160
-    height: 800
-    width: 480
+    density: 480
+    height: 1920
+    width: 1080
   }
 }