Hold a reference to any kind of context in WindowAndroid.

ui/android/java/src/org/chromium/ui/base/WindowAndroid.java

Index: ui/android/java/src/org/chromium/ui/base/WindowAndroid.java
diff --git a/ui/android/java/src/org/chromium/ui/base/WindowAndroid.java b/ui/android/java/src/org/chromium/ui/base/WindowAndroid.java
index 3d775de11c9f19e5be9260380f87fbb609a9f2fa..8b1b081919322831328a81066ec0b76ddc2c6e5e 100644
--- a/ui/android/java/src/org/chromium/ui/base/WindowAndroid.java
+++ b/ui/android/java/src/org/chromium/ui/base/WindowAndroid.java
@@ -77,6 +77,11 @@ public class WindowAndroid {
 
     protected Context mApplicationContext;
     protected SparseArray<IntentCallback> mOutstandingIntents;
+    // To render properly on an external display through a Presentation we need to fetch

[Ted C, 2015/11/11 00:19:45]

This comment seems more like the CL description than what should be in this
file.

This is just the reference to the context and it is a weak ref to avoid leaking.

Why it is needed seems like something that will quickly go out of date when the
next caller uses getContext() for something else.  Then they're left wondering
if it should only be used if it's a Presentation, etc..., etc...

[gsennton, 2015/11/13 20:00:05]

Done.

+    // display metrics from the context provided by the Presentation. This context is not the same
+    // as the application context since the application context targets the primary display.
+    // We use a weak reference here to prevent this from leaking in WebView.
+    private WeakReference<Context> mContextRef;
 
     // Ideally, this would be a SparseArray<String>, but there's no easy way to store a
     // SparseArray<String> in a bundle during saveInstanceState(). So we use a HashMap and suppress
@@ -136,13 +141,20 @@ public class WindowAndroid {
      */
     @SuppressLint("UseSparseArrays")
     public WindowAndroid(Context context) {
-        assert context == context.getApplicationContext();
-        mApplicationContext = context;
+        mApplicationContext = context.getApplicationContext();
+        // context does not have the same lifetime guarantees as an application context so we can't
+        // hold a strong reference to it.
+        mContextRef = new WeakReference<Context>(context);
         mOutstandingIntents = new SparseArray<IntentCallback>();
         mIntentErrors = new HashMap<Integer, String>();
         mVSyncMonitor = new VSyncMonitor(context, mVSyncListener);
-        mAccessibilityManager = (AccessibilityManager)
-                context.getSystemService(Context.ACCESSIBILITY_SERVICE);
+        mAccessibilityManager = (AccessibilityManager) mApplicationContext.getSystemService(
+                Context.ACCESSIBILITY_SERVICE);
+    }
+
+    @CalledByNative
+    private static WindowAndroid createForTesting(Context context) {
+        return new WindowAndroid(context);
     }
 
     /**
@@ -583,6 +595,11 @@ public class WindowAndroid {
         });
     }
 
+    public WeakReference<Context> getContext() {

[Ted C, 2015/11/11 00:19:45]

add javadoc (probably should add a warning that makes it clear that the caller
should make no assumptions what type of context this is i.e. an activity,
etc...)

[gsennton, 2015/11/13 20:00:05]

Done.

+        // Return a new WeakReference to prevent clients from releasing our internal WeakReference.
+        return new WeakReference<Context>(mContextRef.get());
+    }
+
     /**
      * Update whether the placeholder is 'drawn' based on whether an animation is running
      * or touch exploration is enabled - if either of those are true, we call