Fix broken VR transitions due to ChromeTabbedActivity not being exported.

chrome/android/java/AndroidManifest.xml

Index: chrome/android/java/AndroidManifest.xml
diff --git a/chrome/android/java/AndroidManifest.xml b/chrome/android/java/AndroidManifest.xml
index 189d816d37a066dbb3b6143fceb8c3c1d05817e7..ec4c1eb91404dd3d6afc71924d2fef98de15acde 100644
--- a/chrome/android/java/AndroidManifest.xml
+++ b/chrome/android/java/AndroidManifest.xml
@@ -53,7 +53,8 @@ by a child template that "extends" this file.
     <uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE"/>
     <uses-permission android:name="android.permission.WRITE_SYNC_SETTINGS"/>
     {% set enable_vr_shell = enable_vr_shell|default(0) %}
-    {% if enable_vr_shell == "true" %}
+    {% set enable_webvr = enable_webvr|default(0) %}
+    {% if enable_vr_shell == "true" or enable_webvr == "true" %}
     <!-- Required to read the paired viewer's distortion parameters. -->
     <uses-permission android:name="android.permission.READ_EXTERNAL_STORAGE"/>
     <!-- Indicates use of Android's VR-mode, available only on Android N+. -->
@@ -347,29 +348,48 @@ by a child template that "extends" this file.
 
         <!-- ChromeTabbedActivity related -->
         <activity android:name="org.chromium.chrome.browser.ChromeTabbedActivity"
-             android:theme="@style/TabbedModeTheme"
-             android:exported="false"
-             android:windowSoftInputMode="adjustResize"
-             android:launchMode="singleTask"
-             android:configChanges="orientation|keyboardHidden|keyboard|screenSize|mcc|mnc|screenLayout|smallestScreenSize"
-             android:hardwareAccelerated="false">
-            {% set enable_webvr = enable_webvr|default(0) %}
-            {% if enable_vr_shell == "true" or enable_webvr == "true" %}
+            android:theme="@style/TabbedModeTheme"
+            android:exported="false"
+            android:windowSoftInputMode="adjustResize"
+            android:launchMode="singleTask"
+            android:configChanges="orientation|keyboardHidden|keyboard|screenSize|mcc|mnc|screenLayout|smallestScreenSize"
+            android:hardwareAccelerated="false">
+            <!--
+              See the VRChromeTabbedActivity alias below for an explanation of this dummy intent
+              filter. We need to add these filters here as well, or non-presenting webVR pages will
+              trigger a daydream incompatible app message.
+            -->
             <intent-filter>
-                <!-- Add a dummy action to match intent without any action. -->
                 <action android:name="org.chromium.chrome.browser.dummy.action" />
-                <!--
-                  Daydream api categorizes an activity to three categories: Cardboard only, hybrid
-                  or Daydream. It does so by testing if intents can be resolved by the activity
-                  that requests it.
-                  In Chrome, CTA is the activity that uses Daydream api and we want to be in hybrid
-                  category. So add an intent filter that could pass Daydream tests here.
-                -->
                 <category android:name="com.google.intent.category.DAYDREAM" />
                 <category android:name="com.google.intent.category.CARDBOARD" />
             </intent-filter>
-            {% endif %}
         </activity>
+
+        {% if enable_vr_shell == "true" or enable_webvr == "true" %}
+        <!--
+            TODO(mthiesse): Temporarily skip ChromeLauncherActivity when returning from Daydream
+            DON flow to avoid polluting metrics.
+        -->
+        <activity-alias android:name="org.chromium.chrome.browser.VRChromeTabbedActivity"
+            android:targetActivity="org.chromium.chrome.browser.ChromeTabbedActivity"
+            android:exported="true"

[Ted C, 2016/11/16 18:07:00]

Sorry, but I don't think we can/should do this.

By doing this, external applications will be able to send intents directly to
ChromeTabbedActivity (if they hardcode the classname as that bypasses the intent
filters).

This means any sanitizing of intents we do in ChromeLauncher would be skipped,
which is why we don't export our activities as it ensures a single place to do
this.

Also, it would allow third parties to change Chrome's behavior by bypassing our
access point.

[mthiesse, 2016/11/16 18:45:12]

Ah, yes thanks for pointing that out. I've switched to using pendingIntents and
their API seems to be fine with that.

The alias is no longer exported, though we should keep it around for the
enableVrMode flag so that the transition is less jarring.

+            android:enableVrMode="@string/gvr_vr_mode_component">
+            <!--
+              Daydream api categorizes an activity to three categories: Cardboard only, hybrid
+              or Daydream. It does so by testing if intents can be resolved by the activity
+              that requests it.
+              In Chrome, CTA is the activity that uses Daydream api and we want to be in hybrid
+              category. So add an intent filter that could pass Daydream tests here.
+            -->
+            <intent-filter>
+                <action android:name="org.chromium.chrome.browser.dummy.action" />
+                <category android:name="com.google.intent.category.DAYDREAM" />
+                <category android:name="com.google.intent.category.CARDBOARD" />
+            </intent-filter>
+        </activity-alias>
+        {% endif %}
+
         <activity android:name="org.chromium.chrome.browser.ChromeTabbedActivity2"
              android:theme="@style/TabbedModeTheme"
              android:exported="false"