Cherry pick: [Android] Ignore isSystemKey from the framework.

BUG: 14438911

Upstream bug description:
[Android] Ignore isSystemKey from the framework.

Force isSystemKey flag to false as the Android framework is changing
this behavior and this is breaking DPAD keys.

Review URL: https://codereview.chromium.org/267903005/

Change-Id: Ic0711886412640696ad9cfca04877046a6b588bb
diff --git a/content/public/android/java/src/org/chromium/content/browser/input/ImeAdapter.java b/content/public/android/java/src/org/chromium/content/browser/input/ImeAdapter.java
index fa1a50c..1f87b13 100644
--- a/content/public/android/java/src/org/chromium/content/browser/input/ImeAdapter.java
+++ b/content/public/android/java/src/org/chromium/content/browser/input/ImeAdapter.java
@@ -375,7 +375,7 @@
         mViewEmbedder.onImeEvent(false);
         return nativeSendKeyEvent(mNativeImeAdapterAndroid, event, event.getAction(),
                 getModifiers(event.getMetaState()), event.getEventTime(), event.getKeyCode(),
-                                event.isSystem(), event.getUnicodeChar());
+                             /*isSystemKey=*/false, event.getUnicodeChar());
     }
 
     boolean sendSyntheticKeyEvent(int eventType, long timestampMs, int keyCode, int unicodeChar) {