Fix shader_disk_cache.cc not running the clearing callback when cache is empty

The ShaderClearHelper never runs the callback if there is no cache to clear.
Clearing shader cache is part of the BrowsingDataRemover's procedure when
DATA_TYPE_CACHE flag is set. So this results in BrowsingDataRemover never
reporting completion to its observers.

Bug: 1020168
Change-Id: I23ba6ed2a99b6c44acf0b349dd398f26133369a9
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1890310Reviewed-by: Kenneth Russell <kbr@chromium.org>
Reviewed-by: Bo <boliu@chromium.org>
Commit-Queue: Pavel Shmakov <pshmakov@chromium.org>
Cr-Commit-Position: refs/heads/master@{#711359}

gpu/ipc/host/shader_disk_cache.cc

@@ -469,6 +469,10 @@ void ShaderCacheFactory::ClearByPath(const base::FilePath& path,
                                      base::OnceClosure callback) {
   DCHECK(CalledOnValidThread());
   DCHECK(!callback.is_null());
+  if (path.empty()) {
+    std::move(callback).Run();
+    return;
+  }
 
   auto helper = std::make_unique<ShaderClearHelper>(this, GetByPath(path), path,
                                                     delete_begin, delete_end,

gpu/ipc/host/shader_disk_cache_unittest.cc

@@ -79,6 +79,23 @@ TEST_F(ShaderDiskCacheTest, ClearsCache) {
   EXPECT_EQ(0, cache->Size());
 }
 
+TEST_F(ShaderDiskCacheTest, ClearByPathTriggersCallback) {
+  InitCache();
+  factory()->Get(kDefaultClientId)->Cache(kCacheKey, kCacheValue);
+  net::TestCompletionCallback test_callback;
+  factory()->ClearByPath(cache_path(), base::Time(), base::Time::Max(),
+      base::BindLambdaForTesting([&]() { test_callback.callback().Run(1); } ));
+  ASSERT_TRUE(test_callback.WaitForResult());
+}
+
+// Important for clearing in-memory profiles.
+TEST_F(ShaderDiskCacheTest, ClearByPathWithEmptyPathTriggersCallback) {
+  net::TestCompletionCallback test_callback;
+  factory()->ClearByPath(base::FilePath(), base::Time(), base::Time::Max(),
+      base::BindLambdaForTesting([&]() { test_callback.callback().Run(1); } ));
+  ASSERT_TRUE(test_callback.WaitForResult());
+}
+
 // For https://crbug.com/663589.
 TEST_F(ShaderDiskCacheTest, SafeToDeleteCacheMidEntryOpen) {
   InitCache();

weblayer/shell/android/javatests/src/org/chromium/weblayer/test/DataClearingTest.java

@@ -48,10 +48,16 @@ public class DataClearingTest {
 
     @Test
     @SmallTest
-    public void clearCache_TriggersCallback() throws InterruptedException {
+    public void clearCacheWithPersistedProfile_TriggersCallback() throws InterruptedException {
         checkTriggersCallbackOnClearData(new int[] {CACHE}, "Profile");
     }
 
+    @Test
+    @SmallTest
+    public void clearCacheWithInMemoryProfile_TriggersCallback() throws InterruptedException {
+        checkTriggersCallbackOnClearData(new int[] {CACHE}, "");
+    }
+
     @Test
     @SmallTest
     public void clearMultipleTypes_TriggersCallback() throws InterruptedException {