Refactor Android printing code to make it more testable.

printing/android/java/src/org/chromium/printing/PrintingControllerImpl.java

Index: printing/android/java/src/org/chromium/printing/PrintingControllerImpl.java
diff --git a/printing/android/java/src/org/chromium/printing/PrintingControllerImpl.java b/printing/android/java/src/org/chromium/printing/PrintingControllerImpl.java
index 34c4dc404c16b884d7c9f43217df96cd21e5a601..27869af64bcc2beceb0bfbdfac6f08c96734082b 100644
--- a/printing/android/java/src/org/chromium/printing/PrintingControllerImpl.java
+++ b/printing/android/java/src/org/chromium/printing/PrintingControllerImpl.java
@@ -4,7 +4,11 @@
 
 package org.chromium.printing;
 
+import org.chromium.base.ThreadUtils;
+
+import android.annotation.SuppressLint;
 import android.content.Context;
+import android.os.Build;
 import android.os.Bundle;
 import android.os.CancellationSignal;
 import android.os.ParcelFileDescriptor;
@@ -17,8 +21,6 @@ import android.print.PrintDocumentAdapter;
 import android.print.PrintDocumentAdapter.LayoutResultCallback;
 import android.print.PrintDocumentAdapter.WriteResultCallback;
 import android.print.PrintDocumentInfo;
-import android.print.PrintJob;
-import android.print.PrintManager;
 import android.util.Log;
 
 import java.io.IOException;
@@ -35,15 +37,16 @@ import java.util.List;
  * print button. The singleton object lives in UI thread. Interaction with the native side is
  * carried through PrintingContext class.
  */
-class PrintingControllerImpl extends PrintDocumentAdapter implements PrintingController {
+public class PrintingControllerImpl extends PrintDocumentAdapter implements PrintingController {
 
-    private static final String LOG_TAG = "PrintingControllerImpl";
+    /** The singleton instance for this class. */
+    private static PrintingController sInstance;
 
-    private static final String PDF_FILE_NAME = "chrome_print_document.pdf";
+    private static final String LOG_TAG = "PrintingControllerImpl";
 
     private String mErrorMessage;
 
-    private final PrintManager mPrintManager;
+    private final PrintManagerDelegate mPrintManager;
 
     private PrintingContextInterface mPrintingContext;
 
@@ -91,18 +94,55 @@ class PrintingControllerImpl extends PrintDocumentAdapter implements PrintingCon
     /** Total number of pages to print with initial print dialog settings. */
     private int mLastKnownMaxPages = PrintDocumentInfo.PAGE_COUNT_UNKNOWN;
 
-    PrintingControllerImpl(final Context context) {
-        mPrintManager = (PrintManager) context.getSystemService(Context.PRINT_SERVICE);
+    private PrintingControllerImpl(final PrintManagerDelegate printManager, String errorText) {
+        mPrintManager = printManager;
+        mErrorMessage = errorText;
     }
 
-    @Override
-    public boolean hasPrintingFinished() {
-      return mPrintingState == PRINTING_STATE_FINISHED;
+    /**
+     * Creates a controller for handling printing with the framework.
+     *
+     * The controller is a singleton, since there can be only one printing action at any time.

[whywhat, 2013/11/19 15:39:32]

Is this going to be true with the window.print() support?
Also, why do we need such a strange singleton pattern with create() and
instance() ?

[cimamoglu1, 2013/11/19 17:40:33]

We don't "need", but this is nicer approach:
For creation, we need the print manager and error text, but afterwards we don't
need them to get the created instance.
We would need to pass dummy values. In any case, the passed values would be
useless. With this approach, create does what it needs to, and getInstance does
what it needs to do.

+     *
+     * @param printManager
+     * @param errorText The error message to be shown to user in case something goes wrong in PDF
+     *                  generation in Chromium. We pass it here as a string so src/printing/android
+     *                  doesn't need any string dependency.
+     * @return The resulting PrintingController.
+     */
+    public static PrintingController create(final PrintManagerDelegate printManager,
+           String errorText) {
+      ThreadUtils.assertOnUiThread();

[bulach, 2013/11/19 15:32:22]

nit: indent this block

[cimamoglu1, 2013/11/19 17:40:33]

Done.

+
+      if (sInstance == null) {
+        sInstance = new PrintingControllerImpl(printManager, errorText);

[whywhat, 2013/11/19 15:39:32]

also, Java indent is 4 spaces so indent this line two spaces more from within
the outside block 

[cimamoglu1, 2013/11/19 17:40:33]

Done.

+      }
+      return sInstance;
+    }
+
+    /**
+     * Returns the singleton instance, created by the {@link PrintingControllerImpl#create}.
+     *
+     * This method must be called once {@link PrintingControllerImpl#create} is called, and always
+     * thereafter.
+     *
+     * @return The singleton instance.
+     */
+    public static PrintingController getInstance() {
+        return sInstance;
+    }
+
+    /**
+     * @return True if the running version of the Android supports printing.
+     */
+    @SuppressLint("InlinedApi")
+    public static boolean isPrintingSupported() {
+        return Build.VERSION.SDK_INT >= Build.VERSION_CODES.KITKAT;
     }
 
     @Override
-    public void setErrorText(final String errorText) {
-      mErrorMessage = errorText;
+    public boolean hasPrintingFinished() {
+      return mPrintingState == PRINTING_STATE_FINISHED;
     }
 
     @Override
@@ -203,8 +243,7 @@ class PrintingControllerImpl extends PrintDocumentAdapter implements PrintingCon
             mLastKnownMaxPages = maxPages;
         }
         if (mPrintingState == PRINTING_STATE_STARTED_FROM_ONLAYOUT) {
-            // TODO(cimamoglu): Choose a meaningful filename.
-            PrintDocumentInfo info = new PrintDocumentInfo.Builder(PDF_FILE_NAME)
+            PrintDocumentInfo info = new PrintDocumentInfo.Builder(mPrintable.getTitle())
                     .setContentType(PrintDocumentInfo.CONTENT_TYPE_DOCUMENT)
                     .setPageCount(mLastKnownMaxPages)
                     .build();