Make WebView respond to device scale change

content/browser/android/content_view_core_impl.cc

Index: content/browser/android/content_view_core_impl.cc
diff --git a/content/browser/android/content_view_core_impl.cc b/content/browser/android/content_view_core_impl.cc
index 0ea0aea9de0494e69ff800916624fa7136265ecf..2cc9d404c1add568cf8303dd6861be855db65146 100644
--- a/content/browser/android/content_view_core_impl.cc
+++ b/content/browser/android/content_view_core_impl.cc
@@ -919,6 +919,13 @@ void ContentViewCoreImpl::SetFocus(JNIEnv* env,
   SetFocusInternal(focused);
 }
 
+void ContentViewCoreImpl::SetDeviceScaleFactor(JNIEnv* env,
+                                               const JavaParamRef<jobject>& obj,
+                                               jfloat device_scale) {
+  DVLOG(1) << __FUNCTION__ << " " << device_scale;
+  dpi_scale_ = device_scale;

[boliu, 2016/08/02 18:09:27]

this should probably do more than just set the value, what about updating
everything that depends on this value?

[Tima Vaisburd, 2016/08/16 00:21:01]

Did not quite get your idea. I think everything that uses dpi_scale() (which is
private) is either event coordinates or rectangle coordinates and they are
transient, except for one thing - AndroidWindow::content_offset() - which I
fixed now.

+}
+
 void ContentViewCoreImpl::SetFocusInternal(bool focused) {
   if (!GetRenderWidgetHostViewAndroid())
     return;