[Android] Read the *last* N lines of a logcat to associate with a crash.

chrome/android/junit/src/org/chromium/chrome/browser/crash/LogcatExtractionCallableTest.java

Index: chrome/android/junit/src/org/chromium/chrome/browser/crash/LogcatExtractionCallableTest.java
diff --git a/chrome/android/junit/src/org/chromium/chrome/browser/crash/LogcatExtractionCallableTest.java b/chrome/android/junit/src/org/chromium/chrome/browser/crash/LogcatExtractionCallableTest.java
index e527f05213f4730cf7ddd56acb819f5dc6d88eb5..51d7840e2d86f84372c59f2e884f99704028a936 100644
--- a/chrome/android/junit/src/org/chromium/chrome/browser/crash/LogcatExtractionCallableTest.java
+++ b/chrome/android/junit/src/org/chromium/chrome/browser/crash/LogcatExtractionCallableTest.java
@@ -130,10 +130,11 @@ public class LogcatExtractionCallableTest {
     public void testLogcatEmpty() {
         final String original = "";
         List<String> expected = new LinkedList<>();
-        List<String> logcat = null;
+        List<String> logcat = new LinkedList<>();
         try {
-            logcat = LogcatExtractionCallable.extractLogcatFromReader(
-                    new BufferedReader(new StringReader(original)), MAX_LINES);
+            boolean inMicrodump = LogcatExtractionCallable.extractLogcatChunkFromReader(
+                    new BufferedReader(new StringReader(original)), MAX_LINES, false, logcat);
+            assertEquals(false, inMicrodump);
         } catch (Exception e) {
             fail(e.toString());
         }
@@ -149,8 +150,8 @@ public class LogcatExtractionCallableTest {
 
     @Test
     public void testLogcatWithoutBeginOrEnd_largeLogcat() {
-        final List<String> original = Arrays.asList("Line 1", "Line 2", "Line 3", "Line 4",
-                "Line 5", "Redundant Line 1", "Redundant Line 2");
+        final List<String> original = Arrays.asList("Trimmed Line 1", "Trimmed Line 2", "Line 1",
+                "Line 2", "Line 3", "Line 4", "Line 5");
         final List<String> expected = Arrays.asList("Line 1", "Line 2", "Line 3", "Line 4",
                 "Line 5");
         assertLogcatLists(expected, original);
@@ -208,14 +209,62 @@ public class LogcatExtractionCallableTest {
         assertLogcatLists(expected, original);
     }
 
+    @Test
+    public void testLogcatReadInMultipleChunks() {
+        final List<String> originalChunk1 = Arrays.asList("Line 1", "Line 2", "Line 3", "Line 4");
+        final List<String> originalChunk2 = Arrays.asList("Line 5", "Line 6", "Line 7", "Line 8");
+        final List<String> expected =
+                Arrays.asList("Line 4", "Line 5", "Line 6", "Line 7", "Line 8");
+        List<String> actualLogcat = new LinkedList<>();
+        boolean inMicrodump = false;
+        try {
+            // Simulate a file reader to test whether the extraction process successfully strips
+            // microdump from logcat.
+            inMicrodump = LogcatExtractionCallable.extractLogcatChunkFromReader(
+                    new BufferedReader(new StringReader(TextUtils.join("\n", originalChunk1))),
+                    MAX_LINES, inMicrodump, actualLogcat);
+            LogcatExtractionCallable.extractLogcatChunkFromReader(
+                    new BufferedReader(new StringReader(TextUtils.join("\n", originalChunk2))),
+                    MAX_LINES, inMicrodump, actualLogcat);
+        } catch (Exception e) {
+            fail(e.toString());
+        }
+        assertArrayEquals(expected.toArray(), actualLogcat.toArray());
+    }
+
+    @Test
+    public void testLogcatReadInMultipleChunks_WithBeginAndEnd() {
+        final List<String> originalChunk1 = Arrays.asList(
+                "Line 1", "Line 2", END_MICRODUMP, "Line 3", "Line 4", BEGIN_MICRODUMP, "a", "b");
+        final List<String> originalChunk2 =
+                Arrays.asList("c", "d", END_MICRODUMP, "Line 5", "Line 6");
+        final List<String> expected = Arrays.asList("Line 3", "Line 4", "Line 5", "Line 6");
+        List<String> actualLogcat = new LinkedList<>();
+        boolean inMicrodump = false;
+        try {
+            // Simulate a file reader to test whether the extraction process successfully strips
+            // microdump from logcat.
+            inMicrodump = LogcatExtractionCallable.extractLogcatChunkFromReader(
+                    new BufferedReader(new StringReader(TextUtils.join("\n", originalChunk1))),
+                    MAX_LINES, inMicrodump, actualLogcat);
+            LogcatExtractionCallable.extractLogcatChunkFromReader(
+                    new BufferedReader(new StringReader(TextUtils.join("\n", originalChunk2))),
+                    MAX_LINES, inMicrodump, actualLogcat);
+        } catch (Exception e) {
+            fail(e.toString());
+        }
+        assertArrayEquals(expected.toArray(), actualLogcat.toArray());
+    }
+
     private void assertLogcatLists(List<String> expected, List<String> original) {
-        List<String> actualLogcat = null;
+        List<String> actualLogcat = new LinkedList<>();
         String combinedLogcat = TextUtils.join("\n", original);
         try {
-            //simulate a file reader to test whether the extraction process
-            //successfully strips microdump from logcat
-            actualLogcat = LogcatExtractionCallable.extractLogcatFromReader(
-                    new BufferedReader(new StringReader(combinedLogcat)), MAX_LINES);
+            // Simulate a file reader to test whether the extraction process successfully strips
+            // microdump from logcat.
+            LogcatExtractionCallable.extractLogcatChunkFromReader(
+                    new BufferedReader(new StringReader(combinedLogcat)), MAX_LINES, false,
+                    actualLogcat);
         } catch (Exception e) {
             fail(e.toString());
         }