WebView: add {set,get}SafeBrowsingEnabled per WebView

android_webview/apk/java/proguard.flags

Index: android_webview/apk/java/proguard.flags
diff --git a/android_webview/apk/java/proguard.flags b/android_webview/apk/java/proguard.flags
index c4cf0a424c36fe1ffc28419eca6d0faa877490d1..13984ed0dd5f096a996514146db7a5b27ded97c6 100644
--- a/android_webview/apk/java/proguard.flags
+++ b/android_webview/apk/java/proguard.flags
@@ -16,6 +16,11 @@
     public *;
 }
 
+# TODO(ntfschr): remove this once Android O is released (crbug/706631)

[sgurun-gerrit only, 2017/04/11 00:38:52]

I don't think you need to remove it. Just like the ones below, we can leave it.

[Nate Fischer, 2017/04/11 00:58:02]

Done

+-keep class com.android.webview.chromium.ContentSettingsAdapter {
+    public *;
+}
+
 -keep class com.android.webview.chromium.WebViewChromiumFactoryProviderFor* {
     public *;
 }