Make WebView respond to device scale change

content/browser/android/content_view_core_impl.h

 // 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.
 
 #ifndef CONTENT_BROWSER_ANDROID_CONTENT_VIEW_CORE_IMPL_H_
 #define CONTENT_BROWSER_ANDROID_CONTENT_VIEW_CORE_IMPL_H_
 
 #include <stdint.h>
 
 #include <memory>
@@ skipping 210 matching lines @@
   void SetMultiTouchZoomSupportEnabled(
       JNIEnv* env,
       const base::android::JavaParamRef<jobject>& obj,
       jboolean enabled);
 
   long GetNativeImeAdapter(JNIEnv* env,
                            const base::android::JavaParamRef<jobject>& obj);
   void SetFocus(JNIEnv* env,
                 const base::android::JavaParamRef<jobject>& obj,
                 jboolean focused);
+  void SetDeviceScaleFactor(JNIEnv* env,
+                            const base::android::JavaParamRef<jobject>& obj,
+                            jfloat device_scale);
 
   jint GetBackgroundColor(JNIEnv* env, jobject obj);
   void SetAllowJavascriptInterfacesInspection(
       JNIEnv* env,
       const base::android::JavaParamRef<jobject>& obj,
       jboolean allow);
   void AddJavascriptInterface(
       JNIEnv* env,
       const base::android::JavaParamRef<jobject>& obj,
       const base::android::JavaParamRef<jobject>& object,
@@ skipping 211 matching lines @@
   ui::ViewAndroid view_;
 
   // Reference to the current WebContents used to determine how and what to
   // display in the ContentViewCore.
   WebContentsImpl* web_contents_;
 
   // Page scale factor.
   float page_scale_;
 
   // Device scale factor.
-  const float dpi_scale_;
+  float dpi_scale_;
 
   // Observer to notify of lifecyle changes.
   base::ObserverList<ContentViewCoreImplObserver> observer_list_;
 
   // The cache of device's current orientation set from Java side, this value
   // will be sent to Renderer once it is ready.
   int device_orientation_;
 
   bool accessibility_enabled_;
 
   // Manages injecting Java objects.
   scoped_refptr<GinJavaBridgeDispatcherHost> java_bridge_dispatcher_host_;
 
   DISALLOW_COPY_AND_ASSIGN(ContentViewCoreImpl);
 };
 
 bool RegisterContentViewCore(JNIEnv* env);
 
 }  // namespace content
 
 #endif  // CONTENT_BROWSER_ANDROID_CONTENT_VIEW_CORE_IMPL_H_