Add observers for DIP scale change.

android_webview/java/src/org/chromium/android_webview/AwContents.java

Index: android_webview/java/src/org/chromium/android_webview/AwContents.java
diff --git a/android_webview/java/src/org/chromium/android_webview/AwContents.java b/android_webview/java/src/org/chromium/android_webview/AwContents.java
index b48eb8790663a13fed6107c24f77967b78887ff4..9196128e0c4cdabd08a8c66c5882e01f9d89207b 100644
--- a/android_webview/java/src/org/chromium/android_webview/AwContents.java
+++ b/android_webview/java/src/org/chromium/android_webview/AwContents.java
@@ -78,6 +78,7 @@ import org.chromium.ui.base.ActivityWindowAndroid;
 import org.chromium.ui.base.PageTransition;
 import org.chromium.ui.base.ViewAndroidDelegate;
 import org.chromium.ui.base.WindowAndroid;
+import org.chromium.ui.display.DisplayAndroid.DisplayAndroidObserver;
 
 import java.io.File;
 import java.lang.annotation.Annotation;
@@ -99,8 +100,8 @@ import java.util.concurrent.Callable;
  * continuous build & test in the open source SDK-based tree).
  */
 @JNINamespace("android_webview")
-public class AwContents implements SmartClipProvider,
-        PostMessageSender.PostMessageSenderDelegate {
+public class AwContents implements SmartClipProvider, PostMessageSender.PostMessageSenderDelegate,
+                                   DisplayAndroidObserver {

[boliu, 2016/10/18 00:26:25]

use an inner class

[Tima Vaisburd, 2016/10/19 01:15:54]

Done.

     private static final String TAG = "AwContents";
     private static final boolean TRACE = false;
     private static final int NO_WARN = 0;
@@ -1065,10 +1066,7 @@ public class AwContents implements SmartClipProvider,
         installWebContentsObserver();
         mSettings.setWebContents(webContents);
 
-        float dipScale = mContentViewCore.getDeviceScaleFactor();
-        nativeSetDipScale(mNativeAwContents, dipScale);
-        mLayoutSizer.setDIPScale(dipScale);
-        mSettings.setDIPScale(dipScale);
+        onDIPScaleChanged(mWindowAndroid.getWindowAndroid().getDisplay().getDIPScale());
 
         updateContentViewCoreVisibility();
 
@@ -2275,6 +2273,20 @@ public class AwContents implements SmartClipProvider,
                 sentPortIds);
     }
 
+    // Implements DisplayAndroidObserver interface method.
+    @Override
+    public void onRotationChanged(int rotation) {}
+
+    // Implements DisplayAndroidObserver interface method.
+    @Override
+    public void onDIPScaleChanged(float dipScale) {
+        if (TRACE) Log.i(TAG, "%s onDIPScaleChanged dipScale=%f", this, dipScale);
+
+        nativeSetDipScale(mNativeAwContents, dipScale);
+        mLayoutSizer.setDIPScale(dipScale);
+        mSettings.setDIPScale(dipScale);
+    }
+
     /**
      * Creates a message channel and returns the ports for each end of the channel.
      */
@@ -2384,6 +2396,7 @@ public class AwContents implements SmartClipProvider,
         if (TRACE) Log.i(TAG, "%s onAttachedToWindow", this);
         mTemporarilyDetached = false;
         mAwViewMethods.onAttachedToWindow();
+        mWindowAndroid.getWindowAndroid().getDisplay().addObserver(this);
     }
 
     /**
@@ -2392,6 +2405,7 @@ public class AwContents implements SmartClipProvider,
     @SuppressLint("MissingSuperCall")
     public void onDetachedFromWindow() {
         if (TRACE) Log.i(TAG, "%s onDetachedFromWindow", this);
+        mWindowAndroid.getWindowAndroid().getDisplay().removeObserver(this);
         mAwViewMethods.onDetachedFromWindow();
     }