Optimize thumbnail capturing for Tab-to-Grid transition animation

Split the forced live thumbnail capturing out of the normal caching
path. The forced live thumbnail is captured as low-res, and won't be
saved to the cache. This makes it faster so that using it during
the Tab-to-Grid transition animation won't affect the frame rate too
much.

Bug: 968829
Change-Id: I32ffa8553b5aefb29944781404292a8b891d8d80
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1637979
Commit-Queue: Wei-Yin Chen (陳威尹) <wychen@chromium.org>
Reviewed-by: Matthew Jones <mdjones@chromium.org>
Reviewed-by: Yusuf Ozuysal <yusufo@chromium.org>
Cr-Commit-Position: refs/heads/master@{#665691}

chrome/android/features/tab_ui/java/src/org/chromium/chrome/browser/tasks/tab_management/TabListMediator.java

@@ -525,7 +525,6 @@ class TabListMediator {
                 mModel.get(i).set(TabProperties.IS_SELECTED, isSelected);
 
                 if (mThumbnailProvider != null && isSelected) {
-                    // TODO(crbug.com/968829): make force updating faster.
                     ThumbnailFetcher callback = new ThumbnailFetcher(mThumbnailProvider, tab, true);
                     mModel.get(i).set(TabProperties.THUMBNAIL_FETCHER, callback);
                 }

chrome/android/java/src/org/chromium/chrome/browser/compositor/layouts/content/TabContentManager.java

@@ -11,7 +11,6 @@ import android.graphics.Bitmap;
 import android.graphics.Canvas;
 import android.graphics.Matrix;
 import android.support.annotation.NonNull;
-import android.support.annotation.Nullable;
 import android.view.View;
 import android.view.ViewGroup.MarginLayoutParams;
 
@@ -268,7 +267,7 @@ public class TabContentManager {
      * @param forceUpdate Whether to obtain the thumbnail from the live content.
      */
     public void getTabThumbnailWithCallback(
-            Tab tab, Callback<Bitmap> callback, boolean forceUpdate) {
+            @NonNull Tab tab, @NonNull Callback<Bitmap> callback, boolean forceUpdate) {
         if (mNativeTabContentManager == 0 || !mSnapshotsEnabled) return;
 
         if (!forceUpdate) {
@@ -280,11 +279,11 @@ public class TabContentManager {
         // that first even if |forceUpdate|.
         nativeGetTabThumbnailWithCallback(mNativeTabContentManager, tab.getId(), (diskBitmap) -> {
             callback.onResult(diskBitmap);
-            cacheTabThumbnail(tab, (bitmap) -> {
+            captureDownsampledThumbnail(tab, (bitmap) -> {
                 // Null check to avoid having a Bitmap from nativeGetTabThumbnailWithCallback() but
                 // cleared here.
-                // If invalidation is not needed, cacheTabThumbnail() might not do anything and
-                // send back null.
+                // If invalidation is not needed, captureDownsampledThumbnail() might not do
+                // anything and send back null.
                 if (bitmap != null) {
                     callback.onResult(bitmap);
                 }
@@ -297,40 +296,58 @@ public class TabContentManager {
      * @param tab The tab whose content we will cache.
      */
     public void cacheTabThumbnail(@NonNull final Tab tab) {
-        cacheTabThumbnail(tab, null);
+        if (mNativeTabContentManager == 0 || !mSnapshotsEnabled) return;
+
+        if (tab.getNativePage() != null || isNativeViewShowing(tab)) {
+            cacheNativeTabThumbnail(tab);
+        } else {
+            if (tab.getWebContents() == null) return;
+            nativeCacheTab(mNativeTabContentManager, tab, mThumbnailScale);
+        }
+    }
+
+    private Bitmap cacheNativeTabThumbnail(final Tab tab) {
+        assert tab.getNativePage() != null || isNativeViewShowing(tab);
+
+        Bitmap nativeBitmap = readbackNativeBitmap(tab, mThumbnailScale);
+        if (nativeBitmap == null) return null;
+        nativeCacheTabWithBitmap(mNativeTabContentManager, tab, nativeBitmap, mThumbnailScale);
+        return nativeBitmap;
     }
 
     /**
-     * Cache the content of a tab as a thumbnail.
-     * @param tab The tab whose content we will cache.
+     * Capture the downsampled content of a tab as a thumbnail.
+     * @param tab The tab whose content we will capture.
      * @param callback The callback to send the {@link Bitmap} with.
      */
-    public void cacheTabThumbnail(@NonNull final Tab tab, @Nullable Callback<Bitmap> callback) {
-        if (mNativeTabContentManager != 0 && mSnapshotsEnabled) {
+    private void captureDownsampledThumbnail(final Tab tab, @NonNull Callback<Bitmap> callback) {
+        if (mNativeTabContentManager == 0 || !mSnapshotsEnabled) return;
+
+        final float downsamplingScale = 0.5f;
         if (tab.getNativePage() != null || isNativeViewShowing(tab)) {
-                Bitmap nativeBitmap = readbackNativeBitmap(tab, mThumbnailScale);
-                if (nativeBitmap == null) {
-                    if (callback != null) callback.onResult(null);
+            // If we use readbackNativeBitmap() with a downsampled scale and not saving it through
+            // nativeCacheTabWithBitmap(), the logic of InvalidationAwareThumbnailProvider
+            // might prevent cacheTabThumbnail() from getting the latest thumbnail.
+            // Therefore, we have to also call cacheNativeTabThumbnail(), and do the downsampling
+            // here ourselves. This is less efficient than capturing a downsampled bitmap, but
+            // the performance here is not the bottleneck.
+            Bitmap bitmap = cacheNativeTabThumbnail(tab);
+            if (bitmap == null) {
+                callback.onResult(null);
                 return;
             }
-                nativeCacheTabWithBitmap(
-                        mNativeTabContentManager, tab, nativeBitmap, mThumbnailScale);
-                if (callback != null) {
             // In portrait mode, we want to show thumbnails in squares.
             // Therefore, the thumbnail saved in portrait mode needs to be cropped to
             // a square, or it would become too tall and break the layout.
             Matrix matrix = new Matrix();
-                    matrix.setScale(0.5f, 0.5f);
-                    Bitmap resized = Bitmap.createBitmap(nativeBitmap, 0, 0,
-                            nativeBitmap.getWidth(),
-                            min(nativeBitmap.getWidth(), nativeBitmap.getHeight()), matrix, true);
+            matrix.setScale(downsamplingScale, downsamplingScale);
+            Bitmap resized = Bitmap.createBitmap(bitmap, 0, 0, bitmap.getWidth(),
+                    min(bitmap.getWidth(), bitmap.getHeight()), matrix, true);
             callback.onResult(resized);
-                }
-                nativeBitmap.recycle();
         } else {
             if (tab.getWebContents() == null) return;
-                nativeCacheTab(mNativeTabContentManager, tab, mThumbnailScale, callback);
-            }
+            nativeCaptureThumbnail(
+                    mNativeTabContentManager, tab, mThumbnailScale * downsamplingScale, callback);
         }
     }
 
@@ -402,8 +419,10 @@ public class TabContentManager {
     private native void nativeAttachTab(long nativeTabContentManager, Tab tab, int tabId);
     private native void nativeDetachTab(long nativeTabContentManager, Tab tab, int tabId);
     private native boolean nativeHasFullCachedThumbnail(long nativeTabContentManager, int tabId);
-    private native void nativeCacheTab(long nativeTabContentManager, Object tab,
+    private native void nativeCaptureThumbnail(long nativeTabContentManager, Object tab,
             float thumbnailScale, Callback<Bitmap> callback);
+    private native void nativeCacheTab(
+            long nativeTabContentManager, Object tab, float thumbnailScale);
     private native void nativeCacheTabWithBitmap(long nativeTabContentManager, Object tab,
             Object bitmap, float thumbnailScale);
     private native void nativeInvalidateIfChanged(long nativeTabContentManager, int tabId,

chrome/browser/android/compositor/tab_content_manager.cc

@@ -243,14 +243,10 @@ content::RenderWidgetHostView* TabContentManager::GetRwhvForTab(
   if (!rwhv || !rwhv->IsSurfaceAvailableForCopy())
     return nullptr;
 
-  if (!thumbnail_cache_->CheckAndUpdateThumbnailMetaData(tab_id,
-                                                         tab_android->GetURL()))
-    return nullptr;
-
   return rwhv;
 }
 
-void TabContentManager::CacheTab(
+void TabContentManager::CaptureThumbnail(
     JNIEnv* env,
     const JavaParamRef<jobject>& obj,
     const JavaParamRef<jobject>& tab,
@@ -268,12 +264,34 @@ void TabContentManager::CacheTab(
   const int tab_id = tab_android->GetAndroidId();
 
   TabReadbackCallback readback_done_callback = base::BindOnce(
-      &TabContentManager::PutThumbnailIntoCache, weak_factory_.GetWeakPtr(),
+      &TabContentManager::SendThumbnailToJava, weak_factory_.GetWeakPtr(),
       tab_id, base::android::ScopedJavaGlobalRef<jobject>(j_callback));
   pending_tab_readbacks_[tab_id] = std::make_unique<TabReadbackRequest>(
       rwhv, thumbnail_scale, std::move(readback_done_callback));
 }
 
+void TabContentManager::CacheTab(JNIEnv* env,
+                                 const JavaParamRef<jobject>& obj,
+                                 const JavaParamRef<jobject>& tab,
+                                 jfloat thumbnail_scale) {
+  content::RenderWidgetHostView* rwhv = GetRwhvForTab(env, obj, tab);
+  if (!rwhv) {
+    return;
+  }
+  TabAndroid* tab_android = TabAndroid::GetNativeTab(env, tab);
+  DCHECK(tab_android);
+  const int tab_id = tab_android->GetAndroidId();
+  if (!thumbnail_cache_->CheckAndUpdateThumbnailMetaData(
+          tab_id, tab_android->GetURL())) {
+    return;
+  }
+  TabReadbackCallback readback_done_callback =
+      base::BindOnce(&TabContentManager::PutThumbnailIntoCache,
+                     weak_factory_.GetWeakPtr(), tab_id);
+  pending_tab_readbacks_[tab_id] = std::make_unique<TabReadbackRequest>(
+      rwhv, thumbnail_scale, std::move(readback_done_callback));
+}
+
 void TabContentManager::CacheTabWithBitmap(JNIEnv* env,
                                            const JavaParamRef<jobject>& obj,
                                            const JavaParamRef<jobject>& tab,
@@ -289,7 +307,7 @@ void TabContentManager::CacheTabWithBitmap(JNIEnv* env,
   skbitmap.setImmutable();
 
   if (thumbnail_cache_->CheckAndUpdateThumbnailMetaData(tab_id, url))
-    PutThumbnailIntoCache(tab_id, nullptr, thumbnail_scale, skbitmap);
+    PutThumbnailIntoCache(tab_id, thumbnail_scale, skbitmap);
 }
 
 void TabContentManager::InvalidateIfChanged(JNIEnv* env,
@@ -338,7 +356,8 @@ void TabContentManager::GetTabThumbnailWithCallback(
       tab_id,
       base::BindRepeating(
           &TabContentManager::TabThumbnailAvailable, weak_factory_.GetWeakPtr(),
-          base::android::ScopedJavaGlobalRef<jobject>(j_callback)));
+          base::android::ScopedJavaGlobalRef<jobject>(j_callback),
+          /* need_downsampling */ true));
 }
 
 void TabContentManager::OnUIResourcesWereEvicted() {
@@ -351,7 +370,20 @@ void TabContentManager::OnFinishedThumbnailRead(int tab_id) {
       env, weak_java_tab_content_manager_.get(env), tab_id);
 }
 
-void TabContentManager::PutThumbnailIntoCache(
+void TabContentManager::PutThumbnailIntoCache(int tab_id,
+                                              float thumbnail_scale,
+                                              const SkBitmap& bitmap) {
+  TabReadbackRequestMap::iterator readback_iter =
+      pending_tab_readbacks_.find(tab_id);
+
+  if (readback_iter != pending_tab_readbacks_.end())
+    pending_tab_readbacks_.erase(tab_id);
+
+  if (thumbnail_scale > 0 && !bitmap.empty())
+    thumbnail_cache_->Put(tab_id, bitmap, thumbnail_scale);
+}
+
+void TabContentManager::SendThumbnailToJava(
     int tab_id,
     base::android::ScopedJavaGlobalRef<jobject> j_callback,
     float thumbnail_scale,
@@ -363,15 +395,15 @@ void TabContentManager::PutThumbnailIntoCache(
     pending_tab_readbacks_.erase(tab_id);
 
   if (j_callback) {
-    TabThumbnailAvailable(j_callback, true, bitmap);
+    TabThumbnailAvailable(j_callback, /*need_downsampling */ false, true,
+                          bitmap);
+    return;
   }
-
-  if (thumbnail_scale > 0 && !bitmap.empty())
-    thumbnail_cache_->Put(tab_id, bitmap, thumbnail_scale);
 }
 
 void TabContentManager::TabThumbnailAvailable(
     base::android::ScopedJavaGlobalRef<jobject> j_callback,
+    bool need_downsampling,
     bool result,
     SkBitmap bitmap) {
   ScopedJavaLocalRef<jobject> j_bitmap;
@@ -382,11 +414,12 @@ void TabContentManager::TabThumbnailAvailable(
     // be hidden.
     // It's fine to horizontally center-align thumbnail saved in landscape
     // mode.
-    SkIRect dest_subset = {0, 0, bitmap.width() / 2,
-                           std::min(bitmap.width(), bitmap.height()) / 2};
+    int scale = need_downsampling ? 2 : 1;
+    SkIRect dest_subset = {0, 0, bitmap.width() / scale,
+                           std::min(bitmap.width(), bitmap.height()) / scale};
     SkBitmap result_bitmap = skia::ImageOperations::Resize(
-        bitmap, skia::ImageOperations::RESIZE_BETTER, bitmap.width() / 2,
-        bitmap.height() / 2, dest_subset);
+        bitmap, skia::ImageOperations::RESIZE_BETTER, bitmap.width() / scale,
+        bitmap.height() / scale, dest_subset);
     j_bitmap = gfx::ConvertToJavaBitmap(&result_bitmap);
   }
   RunObjectCallbackAndroid(j_callback, j_bitmap);

chrome/browser/android/compositor/tab_content_manager.h

@@ -81,11 +81,15 @@ class TabContentManager : public ThumbnailCacheObserver {
       JNIEnv* env,
       const base::android::JavaParamRef<jobject>& obj,
       jint tab_id);
-  void CacheTab(JNIEnv* env,
+  void CaptureThumbnail(JNIEnv* env,
                         const base::android::JavaParamRef<jobject>& obj,
                         const base::android::JavaParamRef<jobject>& tab,
                         jfloat thumbnail_scale,
                         const base::android::JavaParamRef<jobject>& j_callback);
+  void CacheTab(JNIEnv* env,
+                const base::android::JavaParamRef<jobject>& obj,
+                const base::android::JavaParamRef<jobject>& tab,
+                jfloat thumbnail_scale);
   void CacheTabWithBitmap(JNIEnv* env,
                           const base::android::JavaParamRef<jobject>& obj,
                           const base::android::JavaParamRef<jobject>& tab,
@@ -126,7 +130,10 @@ class TabContentManager : public ThumbnailCacheObserver {
       JNIEnv* env,
       const base::android::JavaParamRef<jobject>& obj,
       const base::android::JavaParamRef<jobject>& tab);
-  void PutThumbnailIntoCache(
+  void PutThumbnailIntoCache(int tab_id,
+                             float thumbnail_scale,
+                             const SkBitmap& bitmap);
+  void SendThumbnailToJava(
       int tab_id,
       base::android::ScopedJavaGlobalRef<jobject> j_callback,
       float thumbnail_scale,
@@ -134,6 +141,7 @@ class TabContentManager : public ThumbnailCacheObserver {
 
   void TabThumbnailAvailable(
       base::android::ScopedJavaGlobalRef<jobject> j_callback,
+      bool need_downsampling,
       bool result,
       SkBitmap bitmap);