Add tinted static UI resource cache

ui/android/resources/resource_manager_impl.cc

Index: ui/android/resources/resource_manager_impl.cc
diff --git a/ui/android/resources/resource_manager_impl.cc b/ui/android/resources/resource_manager_impl.cc
index 61c7bdad554d3f7999494da3fad752f8e48e2726..96a4a2d9efaa855fffa7df1c4b615d3fee143fad 100644
--- a/ui/android/resources/resource_manager_impl.cc
+++ b/ui/android/resources/resource_manager_impl.cc
@@ -14,6 +14,9 @@
 #include "base/trace_event/trace_event.h"
 #include "cc/resources/scoped_ui_resource.h"
 #include "jni/ResourceManager_jni.h"
+#include "third_party/skia/include/core/SkBitmap.h"
+#include "third_party/skia/include/core/SkCanvas.h"
+#include "third_party/skia/include/core/SkColorFilter.h"
 #include "ui/android/resources/ui_resource_provider.h"
 #include "ui/android/window_android.h"
 #include "ui/gfx/android/java_bitmap.h"
@@ -24,6 +27,13 @@ using base::android::JavaRef;
 
 namespace ui {
 
+namespace {
+// The maximum number of tinted variations of a single resource.
+// TODO(mdjones): Implement real caching logic; something similar to priority

[aelias_OOO_until_Jul13, 2016/08/31 17:12:26]

If this is worth doing, we should do it before landing instead of leaving it as
indefinite TODO.  But I'd rather we looked for non-memory-using solutions first.

[mdjones, 2016/08/31 17:41:00]

I'll look at this if we determine this is an appropriate solution.

+// that is used by the thumbnails.
+const int kMaxTintResourceCount = 30;

[mdjones, 2016/08/31 17:49:12]

I can also reduce the memory footprint to max of 2mb by reducing the cache size
to 8 resources (at xxxhdpi).

+}  // namespace
+
 // static
 ResourceManagerImpl* ResourceManagerImpl::FromJavaObject(jobject jobj) {
   return reinterpret_cast<ResourceManagerImpl*>(
@@ -73,6 +83,73 @@ ResourceManager::Resource* ResourceManagerImpl::GetResource(
   return resource;
 }
 
+ResourceManager::Resource* ResourceManagerImpl::GetStaticResourceWithTint(
+    int res_id,
+    int tint_color,
+    int default_color) {
+  ResourceMap* resource_map = tinted_resources_.Lookup(tint_color);
+  if (!resource_map) {
+    resource_map = new ResourceMap();
+    tinted_resources_.AddWithID(resource_map, tint_color);
+  } else if (resource_map->size() >= kMaxTintResourceCount) {
+    // If the cache is too large, use the default color for the resource.
+    resource_map = tinted_resources_.Lookup(default_color);
+  }
+
+  Resource* tinted_resource = resource_map->Lookup(res_id);
+
+  // If the resource is already cached, use it.
+  if (tinted_resource)
+    return tinted_resource;
+
+  ResourceManager::Resource* base_image =
+      GetResource(ANDROID_RESOURCE_TYPE_STATIC, res_id);
+  if (!base_image)
+    return nullptr;
+
+  SkBitmap tinted_bitmap;
+  tinted_bitmap.allocPixels(SkImageInfo::MakeN32Premul(base_image->size.width(),
+      base_image->size.height()));
+
+  SkCanvas canvas(tinted_bitmap);
+  canvas.clear(SK_ColorTRANSPARENT);
+
+  // Build a color filter to use on the base resource. This filter multiplies
+  // the RGB components by the components of the new color but retains the
+  // alpha of the original image.
+  SkPaint color_filter;
+  SkScalar color_matrix[] = {
+      SkColorGetR(tint_color) / 255.0f, 0, 0, 0, 0,
+      0, SkColorGetG(tint_color) / 255.0f, 0, 0, 0,
+      0, 0, SkColorGetB(tint_color) / 255.0f, 0, 0,
+      0, 0, 0, 1.0f, 0
+  };
+  color_filter.setColorFilter(
+      SkColorFilter::MakeMatrixFilterRowMajor255(color_matrix));
+
+  // Draw the resource and make it immutable.
+  base_image->ui_resource->GetBitmap(base_image->ui_resource->id(), false).Draw(
+      canvas, color_filter);
+  tinted_bitmap.setImmutable();
+
+  // Create a UI resource from the new bitmap.
+  tinted_resource = new Resource();
+  tinted_resource->size = gfx::Size(base_image->size);
+  tinted_resource->padding = gfx::Rect(base_image->padding);
+  tinted_resource->aperture = gfx::Rect(base_image->aperture);
+  tinted_resource->ui_resource = cc::ScopedUIResource::Create(host_,
+      cc::UIResourceBitmap(tinted_bitmap));
+
+  resource_map->AddWithID(tinted_resource, res_id);
+
+  return tinted_resource;
+}
+
+void ResourceManagerImpl::ClearTintedResourceCache(JNIEnv* env,
+    const JavaRef<jobject>& jobj) {
+  tinted_resources_.Clear();
+}
+
 void ResourceManagerImpl::PreloadResource(AndroidResourceType res_type,
                                           int res_id) {
   DCHECK_GE(res_type, ANDROID_RESOURCE_TYPE_FIRST);