Add "Request app banner" context menu in DevTools

chrome/android/java/src/org/chromium/chrome/browser/banners/AppBannerManager.java

Index: chrome/android/java/src/org/chromium/chrome/browser/banners/AppBannerManager.java
diff --git a/chrome/android/java/src/org/chromium/chrome/browser/banners/AppBannerManager.java b/chrome/android/java/src/org/chromium/chrome/browser/banners/AppBannerManager.java
index 1bfaac7c42c4d1443e60ace2516071355d54dd2d..cd0a59ae9e74325ce7629ea57e28c20970b9b09b 100644
--- a/chrome/android/java/src/org/chromium/chrome/browser/banners/AppBannerManager.java
+++ b/chrome/android/java/src/org/chromium/chrome/browser/banners/AppBannerManager.java
@@ -137,6 +137,11 @@ public class AppBannerManager extends EmptyTabObserver {
         };
     }
 
+    /** Requests the app banner. This method is called from the DevTools. */
+    public void requestAppBanner() {
+        nativeRequestAppBanner(mNativePointer);

[pfeldman, 2016/01/20 04:30:17]

It seems like DevTools uses a different code path to request the app banner
which defeats the emulation purpose. Is there a way to trigger the same code
path instead?

For example, I can see the WebAppBannerClient.h on the Blink level. Can we reuse
it or extend it to do what we need here?

[dominickn, 2016/01/20 05:37:25]

WebAppBannerClient and the other banner Blink bits dispatch an event to the
developer that Chrome has determined that an app banner can be shown. Developers
can then preventDefault() on the event to stop the banner, or redispatch it
later. If the event isn't stopped, Blink calls back to Chromium, telling it to
actually display the banner. All of the real work (checking manifests, origins,
icons, etc. before deciding that a banner is permitted) happens in the browser
process, not in Blink.

In Chromium, banners are first triggered in AppBannerManager:DidFinishLoad,
which is called on navigations to pages. As far as I can see, this CL makes
DevTools call into the same code path by splitting it out of DidFinishLoad and
into RequestAppBanner, triggering it manually from DevTools and from
DidFinishLoad on navigations.

+    }
+
     /** Enables or disables the app banners for testing. */
     @VisibleForTesting
     static void setIsEnabledForTesting(boolean state) {
@@ -173,6 +178,7 @@ public class AppBannerManager extends EmptyTabObserver {
             WebContents webContents);
     private native boolean nativeOnAppDetailsRetrieved(long nativeAppBannerManagerAndroid,
             AppData data, String title, String packageName, String imageUrl);
+    private native void nativeRequestAppBanner(long nativeAppBannerManagerAndroid);
 
     // Testing methods.
     private static native void nativeSetTimeDeltaForTesting(int days);