The answer has to do with the difference between what is considered a "common noun" and what is considered a "proper noun." Proper nouns always get capitalized, common nouns don't, even when used as an adjective. The formal name of anything is a proper noun. Anything that is trademarked, such as, Xerox, Kleenex, Pentium, Phillips, or iPhone is considered a proper noun.

Some words evolve in the course of common usage and lose their capitalization. In formal writing, however, capitalization is also influenced by legal considerations of copyright and trademarking. Thus, non-capitalized, common use is typically accepted by such authorities as the editors of the major dictionaries only when a word or phrase is used ubiquitously as a verb. Thus, "I googled your name yesterday" is acceptable (and now included in the Merriam-Webster's Collegiate Dictionary). But in the examples above, such as, "a Google search produced 7g of carbon dioxide," Google and like terms (YouTube and Chinese) should be capitalized.

The protection of the adjectival usage of trademarks is easier to accomplish than for instances of using trademarked words as either a verb or a noun. Most corporations establish for writers and other people authorized to communicate for the company a list of acceptable nouns with which trademarked names must be paired. For example, you will be hard pressed to find an official Intel publication with the word Pentium used alone. They will always write "Pentium processor." Even the word "Intel" is encouraged to be used as an adjective instead of a noun if it is conveniently possible without compromising meaning. (As an example, Intel's list of trademarks and approved nouns is here.)

There is clearly a "fashion-forward" kind of thinking with regard to dropping unnecessary capitalization and punctuation in printed English wherever possible. And the AP, Reuters, and other journalistic standard bearers seem to be perfectly happy even with letting adjectival and adverbial endings go whenever possible. "China law," for example, instead of "Chinese law" or "Speak soft" instead of "speak softly." Personally, for the most part, I think this trend is wrongheaded, but it is clearly established, accepted, and generally meeting little resistance.

However, even if you accept this overarching trend toward grammatical and typographical minimalism, and even if you a supporter of it, it is still far too early in the game for formal outlets to be dropping capitalization standards for proper nouns, especially in light of copyright and trademark laws. And I actually don't see any legitimate authorities on style and usage making that case, anyway.

All the examples you have here are incorrect uses. All should be capitalized as you surmise.