Add observers for DIP scale change.

content/public/android/java/src/org/chromium/content/browser/ContentViewCore.java

Index: content/public/android/java/src/org/chromium/content/browser/ContentViewCore.java
diff --git a/content/public/android/java/src/org/chromium/content/browser/ContentViewCore.java b/content/public/android/java/src/org/chromium/content/browser/ContentViewCore.java
index 0a5293ba55910c06f9f875e7fbe0115e5489ad2b..543c62b7c1c80c6c6f260116ab2969fcaf9ed1f8 100644
--- a/content/public/android/java/src/org/chromium/content/browser/ContentViewCore.java
+++ b/content/public/android/java/src/org/chromium/content/browser/ContentViewCore.java
@@ -86,6 +86,7 @@ import org.chromium.ui.base.DeviceFormFactor;
 import org.chromium.ui.base.ViewAndroidDelegate;
 import org.chromium.ui.base.WindowAndroid;
 import org.chromium.ui.base.ime.TextInputType;
+import org.chromium.ui.display.DisplayAndroid;
 import org.chromium.ui.display.DisplayAndroid.DisplayAndroidObserver;
 import org.chromium.ui.touch_selection.SelectionEventType;
 
@@ -659,7 +660,10 @@ public class ContentViewCore implements AccessibilityStateChangeListener, Displa
         setContainerViewInternals(internalDispatcher);
 
         mRenderCoordinates.reset();
-        mRenderCoordinates.updateDeviceScaleFactorFromWindow(windowAndroid);
+
+        final float dipScale = windowAndroid.getDisplay().getDIPScale();
+        mRenderCoordinates.setDeviceScaleFactor(dipScale, windowAndroid.getContext());
+        nativeSetDIPScale(mNativeContentViewCore, dipScale, false /* do not force layout */);

[boliu, 2016/10/19 04:19:19]

dipScale should just be part of nativeInit. Then you can avoid this awkward
forceLayout bool

[Tima Vaisburd, 2016/10/19 20:25:11]

Done.

 
         initPopupZoomer(mContext);
         mImeAdapter = createImeAdapter();
@@ -694,9 +698,10 @@ public class ContentViewCore implements AccessibilityStateChangeListener, Displa
         if (!mAttachedToWindow) return;
         WindowAndroid windowAndroid = getWindowAndroid();
         if (windowAndroid != null) {
-            mRenderCoordinates.updateDeviceScaleFactorFromWindow(windowAndroid);
-            windowAndroid.getDisplay().addObserver(this);
-            onRotationChanged(windowAndroid.getDisplay().getRotation());
+            DisplayAndroid display = windowAndroid.getDisplay();
+            display.addObserver(this);
+            onRotationChanged(display.getRotation());
+            onDIPScaleChanged(display.getDIPScale());
         }
     }
 
@@ -3234,6 +3239,7 @@ public class ContentViewCore implements AccessibilityStateChangeListener, Displa
         updateGestureStateListener(GestureEventType.FLING_END);
     }
 
+    // DisplayAndroidObserver method.
     @Override
     public void onRotationChanged(int rotation) {
         // ActionMode#invalidate() won't be able to re-layout the floating
@@ -3266,6 +3272,16 @@ public class ContentViewCore implements AccessibilityStateChangeListener, Displa
         sendOrientationChangeEvent(rotationDegrees);
     }
 
+    // DisplayAndroidObserver method.
+    @Override
+    public void onDIPScaleChanged(float dipScale) {
+        if (getWindowAndroid() == null) return;

[boliu, 2016/10/19 04:19:18]

avoid calling getWindowAndroid twice. it involves jni so not very cheap

[Tima Vaisburd, 2016/10/19 20:25:11]

Done.

+        mRenderCoordinates.setDeviceScaleFactor(dipScale, getWindowAndroid().getContext());
+
+        if (mNativeContentViewCore == 0) return;

[boliu, 2016/10/19 04:19:18]

move this check up as well?

[Tima Vaisburd, 2016/10/19 20:25:11]

Done.

+        nativeSetDIPScale(mNativeContentViewCore, dipScale, true /* force layout */);
+    }
+
     /**
      * Set whether the ContentViewCore requires the WebContents to be fullscreen in order to lock
      * the screen orientation.
@@ -3330,6 +3346,9 @@ public class ContentViewCore implements AccessibilityStateChangeListener, Displa
 
     private native void nativeSetFocus(long nativeContentViewCoreImpl, boolean focused);
 
+    private native void nativeSetDIPScale(
+            long nativeContentViewCoreImpl, float dipScale, boolean forceLayout);
+
     private native void nativeSendOrientationChangeEvent(
             long nativeContentViewCoreImpl, int orientation);