bug 721208 - Tab screenshots can hose the gecko event loop r=mfinkle

mobile/android/base/TabsTray.java

@@ -140,6 +140,7 @@ public class TabsTray extends Activity implements GeckoApp.OnTabsChangedListener
     void finishActivity() {
         finish();
         overridePendingTransition(0, R.anim.shrink_fade_out);
+        GeckoAppShell.sendEventToGecko(new GeckoEvent("Tab:Screenshot:Cancel",""));
     }
 
     // Adapter to bind tabs into a list 

mobile/android/chrome/content/browser.js

@@ -504,7 +504,31 @@ var BrowserApp = {
     this._tabs.splice(this._tabs.indexOf(aTab), 1);
   },
 
+  screenshotQueue: null,
+
   screenshotTab: function screenshotTab(aData) {
+      if (this.screenshotQueue == null) {
+          this.screenShotQueue = [];
+          this.doScreenshotTab(aData);
+      } else {
+          this.screenshotQueue.push(aData);
+      }
+  },
+
+  doNextScreenshot: function() {
+      if (this.screenshotQueue == null || this.screenshotQueue.length == 0) {
+          this.screenshotQueue = null;
+          return;
+      }
+      let data = this.screenshotQueue.pop();
+      if (data == null) {
+          this.screenshotQueue = null;
+          return;
+      }
+      this.doScreenshotTab(data);
+  },
+
+  doScreenshotTab: function doScreenshotTab(aData) {
       let json = JSON.parse(aData);
       let tab = this.getTabForId(parseInt(json.tabID));
       let width = parseInt(json.width);
@@ -899,6 +923,8 @@ var BrowserApp = {
       this._handleTabClosed(this.getTabForId(parseInt(aData)));
     } else if (aTopic == "Tab:Screenshot") {
       this.screenshotTab(aData);
+    } else if (aTopic == "Tab:Screenshot:Cancel") {
+      this.screenshotQueue = null;
     } else if (aTopic == "Browser:Quit") {
       this.quit();
     } else if (aTopic == "SaveAs:PDF") {
@@ -1557,6 +1583,9 @@ Tab.prototype = {
         }
       };
       sendMessageToJava(message);
+      Services.tm.mainThread.dispatch(function() {
+	  BrowserApp.doNextScreenshot()
+      }, Ci.nsIThread.DISPATCH_NORMAL);
   },
 
   updateTransform: function() {