Make WebView respond to device scale change

content/browser/android/content_view_core_impl.cc

 // Copyright 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "content/browser/android/content_view_core_impl.h"
 
 #include <stddef.h>
 
 #include "base/android/jni_android.h"
 #include "base/android/jni_array.h"
@@ skipping 901 matching lines @@
 WebContents* ContentViewCoreImpl::GetWebContents() const {
   return web_contents_;
 }
 
 void ContentViewCoreImpl::SetFocus(JNIEnv* env,
                                    const JavaParamRef<jobject>& obj,
                                    jboolean focused) {
   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;
 
   if (focused)
     GetRenderWidgetHostViewAndroid()->Focus();
   else
     GetRenderWidgetHostViewAndroid()->Blur();
 }
 
@@ skipping 716 matching lines @@
     return ScopedJavaLocalRef<jobject>();
 
   return view->GetJavaObject();
 }
 
 bool RegisterContentViewCore(JNIEnv* env) {
   return RegisterNativesImpl(env) && JNI_DragEvent::RegisterNativesImpl(env);
 }
 
 }  // namespace content