Move screenshot capture to Java-side.

base/test/android/javatests/src/org/chromium/base/test/ScreenshotOnFailureStatement.java

+// Copyright 2017 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+package org.chromium.base.test;
+
+import android.support.test.InstrumentationRegistry;
+import android.support.test.uiautomator.UiDevice;
+
+import org.junit.runners.model.Statement;
+
+import org.chromium.base.CommandLine;
+import org.chromium.base.Log;
+
+import java.io.File;
+
+/**
+ * Statement that captures screenshots if |base| statement fails.
+ *
+ * If --screenshot-path commandline flag is given, this |Statement|
+ * will save a screenshot to the specified path in the case of a test failure.
+ */
+public class ScreenshotOnFailureStatement extends Statement {
+    private static final String TAG = "ScreenshotOnFail";
+
+    private final Statement mBase;
+
+    public ScreenshotOnFailureStatement(final Statement base) {
+        mBase = base;
+    }
+
+    @Override
+    public void evaluate() throws Throwable {
+        try {
+            mBase.evaluate();
+        } catch (Throwable e) {
+            takeScreenshot();

[the real yoland, 2017/05/09 15:23:28]

we should support AssumptionViolatedException here (ignore
AssumptionViolatedException), though our runner currently does not recognized
its result, but in the future we might.

[mikecase (-- gone --), 2017/05/10 02:55:10]

Ack

+            throw e;
+        }
+    }
+
+    private void takeScreenshot() {
+        String screenshotFilePath = CommandLine.isInitialized()

[the real yoland, 2017/05/09 15:23:28]

hmm, there is potentially a better way to do this, by directly passing in
argument to the java runner.

I think communication to test apk should not go though commandline flags, the
base runner might be used for a test apk that doesn't use commandline

we can chat about that in person :)

[mikecase (-- gone --), 2017/05/10 02:55:10]

Done! I agree. I have another CL for render tests where I use command-line
flags. Can't switch that one to use Bundle arguments yet since RenderTests could
theoretically be JUnit3 or 4. These screenshots will always be taken on 4.

+                ? CommandLine.getInstance().getSwitchValue("screenshot-file")
+                : null;
+        if (screenshotFilePath == null) {
+            Log.d(TAG,
+                    "Did not save screenshot of failure. Must specify --screenshot-file "
+                            + "command-line flag to enable this feature.");
+            return;
+        }
+
+        UiDevice uiDevice = UiDevice.getInstance(InstrumentationRegistry.getInstrumentation());
+        File screenshotFile = new File(screenshotFilePath);
+        File screenshotDir = screenshotFile.getParentFile();
+        if (screenshotDir == null) {
+            Log.d(TAG,
+                    String.format(
+                            "Failed to create parent directory for %s. Can't save screenshot.",
+                            screenshotFile));
+            return;
+        }
+        if (!screenshotDir.exists()) {
+            if (!screenshotDir.mkdirs()) {
+                Log.d(TAG,
+                        String.format(
+                                "Failed to create %s. Can't save screenshot.", screenshotDir));
+                return;
+            }
+        }
+        Log.d(TAG, String.format("Saving screenshot of test failure, %s", screenshotFile));
+        uiDevice.takeScreenshot(screenshotFile);
+    }
+}