Fix data() method and add unit test.

I wrote code that called SkAutoTArray::data() and discovered that it
was broken, but not generating compile errors because it's part of a
template and never instantiated anywhere else. I fixed the
implementation and added it to our container unit test to prevent later
regression. This revealed another issue, that "containers in
SkTemplates.h [should] all have a consistent api", according to
test_container_apis. However, data() was never added to the non-array
container APIs. So I added data() to the other containers as well.

Change-Id: I52532c91fdab3fc8c4539053ba8420815b7b0ee5
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/323276
Auto-Submit: John Stiles <johnstiles@google.com>
Commit-Queue: Brian Osman <brianosman@google.com>
Reviewed-by: Brian Osman <brianosman@google.com>

include/private/SkTemplates.h

@@ -114,9 +114,9 @@ public:
         return fArray[index];
     }
 
-    // aliases matching other types like std::vector
-    const T* data() const { return fArray; }
-    T* data() { return fArray; }
+    /** Aliases matching other types, like std::vector. */
+    const T* data() const { return fArray.get(); }
+    T* data() { return fArray.get(); }
 
 private:
     std::unique_ptr<T[]> fArray;
@@ -207,7 +207,7 @@ public:
         return fArray[index];
     }
 
-    // aliases matching other types like std::vector
+    /** Aliases matching other types, like std::vector. */
     const T* data() const { return fArray; }
     T* data() { return fArray; }
     size_t size() const { return fCount; }
@@ -266,6 +266,10 @@ public:
 
     const T& operator[](int index) const { return fPtr.get()[index]; }
 
+    /** Aliases matching other types, like std::vector. */
+    const T* data() const { return fPtr.get(); }
+    T* data() { return fPtr.get(); }
+
     /**
      *  Transfer ownership of the ptr to the caller, setting the internal
      *  pointer to NULL. Note that this differs from get(), which also returns
@@ -335,6 +339,10 @@ public:
         return fPtr[index];
     }
 
+    /** Aliases matching other types, like std::vector. */
+    const T* data() const { return fPtr; }
+    T* data() { return fPtr; }
+
     // Reallocs the array, can be used to shrink the allocation.  Makes no attempt to be intelligent
     void realloc(size_t count) {
         if (count > kCount) {

tests/TemplatesTest.cpp

@@ -77,24 +77,32 @@ constexpr int static kStackPreallocCount = 10;
 template<typename TContainer, typename TCount>
 static void test_container_apis(skiatest::Reporter* reporter) {
     REPORTER_ASSERT(reporter, !TContainer((TCount)0).get());
+    REPORTER_ASSERT(reporter, !TContainer((TCount)0).data());
     REPORTER_ASSERT(reporter, TContainer((TCount)1).get());
+    REPORTER_ASSERT(reporter, TContainer((TCount)1).data());
     REPORTER_ASSERT(reporter, TContainer((TCount)kStackPreallocCount).get());
+    REPORTER_ASSERT(reporter, TContainer((TCount)kStackPreallocCount).data());
     REPORTER_ASSERT(reporter, TContainer((TCount)kStackPreallocCount + 1).get());
+    REPORTER_ASSERT(reporter, TContainer((TCount)kStackPreallocCount + 1).data());
 
     TContainer container;
     // The default constructor may or may not init to empty, depending on the type of container.
 
     container.reset((TCount)1);
     REPORTER_ASSERT(reporter, container.get());
+    REPORTER_ASSERT(reporter, container.get() == container.data());
 
     container.reset((TCount)kStackPreallocCount);
     REPORTER_ASSERT(reporter, container.get());
+    REPORTER_ASSERT(reporter, container.get() == container.data());
 
     container.reset((TCount)kStackPreallocCount + 1);
     REPORTER_ASSERT(reporter, container.get());
+    REPORTER_ASSERT(reporter, container.get() == container.data());
 
     container.reset((TCount)0);
     REPORTER_ASSERT(reporter, !container.get());
+    REPORTER_ASSERT(reporter, !container.data());
 }
 
 DEF_TEST(TemplateContainerAPIs, reporter) {