android_webview: stop using system ICU.

To support unbundled updates we need to stop depending on system
libraries. Disable using the system version of ICU and instead link
Chromium's copy.

This increases binary size by ~7MB.

BUG=409851

Review URL: https://codereview.chromium.org/541753002

Cr-Commit-Position: refs/heads/master@{#293510}

android_webview/android_webview.gyp

@@ -54,6 +54,16 @@
             '-Wl,--fatal-warnings',
           ],
         }],
+        ['android_webview_build==1 and use_system_stlport==1', {
+          # ICU requires RTTI, which is not present in the system's stlport, so
+          # we have to include gabi++. We can't include it in icu.gyp because
+          # link_settings cannot be used inside target_conditions. This will be
+          # removed once we stop using the system stlport.
+          # http://crbug.com/409851
+          'libraries': [
+            '-lgabi++',
+          ],
+        }],
       ],
       'sources': [
         'lib/main/webview_entry_point.cc',

build/common.gypi

@@ -1797,7 +1797,6 @@
 
         # When building as part of the Android system, use system libraries
         # where possible to reduce ROM size.
-        'use_system_icu%': '<(android_webview_build)',
         'use_system_stlport%': '<(android_webview_build)',
 
         # Copy it out one scope.