Fix some flaky tests: Use a dedicated temp dir.

components/crash/android/javatests/src/org/chromium/components/crash/browser/CrashDumpManagerTest.java

Index: components/crash/android/javatests/src/org/chromium/components/crash/browser/CrashDumpManagerTest.java
diff --git a/components/crash/android/javatests/src/org/chromium/components/crash/browser/CrashDumpManagerTest.java b/components/crash/android/javatests/src/org/chromium/components/crash/browser/CrashDumpManagerTest.java
index 53b91f662be5f3c41e920af541aef172bd70cfe8..8a23e9932a2a198da57cf2200394da82b10d2ccb 100644
--- a/components/crash/android/javatests/src/org/chromium/components/crash/browser/CrashDumpManagerTest.java
+++ b/components/crash/android/javatests/src/org/chromium/components/crash/browser/CrashDumpManagerTest.java
@@ -8,10 +8,9 @@ import android.support.test.filters.SmallTest;
 import android.test.InstrumentationTestCase;
 
 import org.chromium.base.ContextUtils;
+import org.chromium.base.FileUtils;
 import org.chromium.base.ThreadUtils;
-import org.chromium.base.test.util.DisabledTest;
 import org.chromium.base.test.util.Feature;
-import org.chromium.base.test.util.TestFileUtil;
 
 import java.io.File;
 import java.io.IOException;
@@ -25,26 +24,24 @@ public class CrashDumpManagerTest extends InstrumentationTestCase {
     @Override
     protected void setUp() throws Exception {
         super.setUp();
+
         ContextUtils.initApplicationContextForTests(
                 getInstrumentation().getTargetContext().getApplicationContext());
-        mTempDir = ContextUtils.getApplicationContext().getCacheDir();
-        assert mTempDir.exists();
+        mTempDir = new File(ContextUtils.getApplicationContext().getCacheDir(), "crash-dump-test");
+        if (mTempDir.exists()) {
+            FileUtils.recursivelyDeleteFile(mTempDir);
+        }
+        assert mTempDir.mkdirs();
     }
 
     @Override
     protected void tearDown() throws Exception {
+        FileUtils.recursivelyDeleteFile(mTempDir);
         super.tearDown();
-        File[] files = mTempDir.listFiles();
-        if (files == null) return;
-
-        for (File file : files) {
-            TestFileUtil.deleteFile(file);
-        }
     }
 
     @SmallTest
     @Feature({"Android-AppBase"})
-    @DisabledTest // Flaky, crbug.com/725379.
     public void testUploadMinidump_NoCallback() throws IOException {
         File minidump = new File(mTempDir, "mini.dmp");
         assertTrue(minidump.createNewFile());
@@ -54,7 +51,6 @@ public class CrashDumpManagerTest extends InstrumentationTestCase {
 
     @SmallTest
     @Feature({"Android-AppBase"})
-    @DisabledTest // Flaky, crbug.com/725379.
     public void testUploadMinidump_NullMinidumpPath() {
         registerUploadCallback(new CrashDumpManager.UploadMinidumpCallback() {
             @Override
@@ -66,9 +62,8 @@ public class CrashDumpManagerTest extends InstrumentationTestCase {
         CrashDumpManager.tryToUploadMinidump(null);
     }
 
-    // @SmallTest
-    // @Feature({"Android-AppBase"})
-    @DisabledTest // Flaky, crbug.com/726976.
+    @SmallTest
+    @Feature({"Android-AppBase"})
     public void testUploadMinidump_FileDoesntExist() {
         registerUploadCallback(new CrashDumpManager.UploadMinidumpCallback() {
             @Override